RetroGaming

I don’t know about the class but you can mod a gameboy for way cheaper than ~$350 and it’s stupid easy to do.

A backlit ips screen is like $60 from us sellers but you can also buy them direct from china for like 1/3-1/2 that. Honestly that’s really the only thing with a crazy markup. The brackets to center the lcd, a new glass lens, etc are like $2-3 each. The install is pretty easy if you can handle disassembling a gameboy and putting it back together. The soldering is 3-5 wires depending on what screen and it’s stupid easy soldering. Some are solder free, the soldering is to just tap the signals for buttons so specific combinations will bring up the screens OSD, some use capacitive touch on the screen bezel instead (or in addition to). Some require minor case modification but that also stupid easy ($2 flush cutters and just remove some plastic ribs, basically)

A lithium battery mod is like $25 domestically and if you can install the normal alkaline batteries you can handle this one. Depending on what battery and what model gameboy you may have to solder 1-2 wires to a usb c board (gba/sp batteries sometimes have it integrated and you can get a replacement battery door with a hole or they come with one (that probably won’t match), gb/color/pocket usually have a daughterboard). The toughest bit is cutting a hole for the usb c charger but if you’re reshelling a lot of replacement shells come with that already done.

Speaking of reshelling that’s also stupid cheap. $10-20 should cover a shell and buttons. That said this can also get stupid expensive for exotic cases (like $100-200+ for boxypixel cases, which are cnc cut aluminum)

So at this point you’re spending 70-100 to do the mods most people do and watching a YouTube video is enough because it’s really easy. If you have no tools a $15 soldering iron beginner kit, $2 flush cutters, a small screwdriver set, and cheap wire strippers will cover everything. Nonconductive tape like kapton is also nice to have (don’t be a hot glue person yuck) but not essential

After that it’s other cheap mods you can add but aren’t typically considered “essential”. LED lighting under the buttons is like $20 and it’s just a flex pcb that you line up and tack on via a few solder points. You can get a fresh speaker, 2 wires to solder. You can also do things like replace the speaker amp but tbh I think this is silly, every gameboy sounds like shit regardless because the speaker is trash. The audio amps are slightly less distorted and louder trash, but still trash. Use headphones if you care that much. An hdmi mod for gba is like $50 and probably the hardest install here, though still fairly easy. Some people recap them while they’re open but I’ve never seen a gameboy with caps that caused issues. Even if you do decide this is worthwhile it’s only really necessary to do electrolytic caps and there aren’t many to do, the sp literally only has 1 (it’s surface mount but stupid easy to do). Iirc the og dmg has the most with 6 and they’re through hole

The main other cost is the console of course. This is where things can be kind of wild. A gameboy confirmed in good working condition can be a little pricey for what it is. Even then it’s still not usually expensive, $50-100 depending on how much of a deal you can find. But this is USA pricing. If you’ll be in Japan I’m sure you can get used gameboys all over for like $20-40, if yahoo jp auctions are any indicator. Buying a broken one is a gamble though they’re usually simple to fix, especially if you’re already planning to replace the screen and speaker. Those and cleaning the power switch/battery contacts fixes 95% of broken gameboys, they’re built like tanks regardless of revision

The idea of a class is neat ig because honestly a lot of sellers sell modded gameboys for $250-300 in the USA but they’re just making bank off of people who watch YouTubers that talk about console modding, think it’s neat, but are too scared to do what’s probably the easiest set of console mods in the world. I don’t do it anymore but I would buy lots of broken gameboys from yahoojp and mod them (buying mods in bulk makes this even cheaper) and easily double or triple my money. Don’t buy from people like me, just do it. It’s so goddamn easy

I've casually perused some Gameboy mods over the years, but never actually done any

And I have no idea what these shops are offering

But to give you an idea of what I've seen out there in general

There's of course shells and buttons, and replacement parts to replace worn/damaged components (and I would imagine that in some cases those new components might be better than the original)

There's options for better screens, and backlit screens on models that didn't originally come with them

USB charging (and charging in general for models that originally used disposable batteries, and higher capacity batteries for those that already had rechargeable)

Video output to hook it up to a TV or whatever

Amplifier circuits and such to improve audio quality

And I'm sure there's others, but that's what I remember seeing off the top of my head.

50000 yen is around $315 right now. I feel like I've seen some places selling pre-modded Gameboys at roughly about that price point, so depending on what they're offering that's potentially a pretty solid deal.

But a lot of mods seem like they're pretty much just a matter of opening the case up and popping the new components into place, and the parts aren't terribly expensive, so you could probably shave some money off by DIYing it at home if you're more interested in having the Gameboy than the experience of going to a workshop to do it. Some mods do require a bit of soldering, it didn't look like it was particularly complicated soldering, but I know that a lot of people just aren't interested in attempting that themselves, don't know what your personal comfort level with that is.

Lots of good advice in this thread, so I'll just addy 2¢. I suck at soldering, but I've modded several GBA, a couple GBC, a couple DS', as well as home consoles. If you can afford it and want to do it for the experience, I'm sure a class would be fun, but if you just want a modded GBA, its incredibly easy. Just make sure you take it slow, and have all the right tool on hand before you get started. Nothing worse than getting halfway through a mod and realizing you need a specific tool in order to continue.