Photography

If you will print at least one sheet per week, I'd definitely consider home, for quality control rather than price per se. Any less often and the damn thing dries up and becomes unusable. I'm assuming inkjet here.

If you want many prints (that are not too big) and like printing, then it might be a good idea to get your own. Also it make sit more worth it, if you like using expensive fine art papers, and preferably you want to sell prints if you print yourself. Keep in mind that those papers cost quite a bit, and inks are not free either. For example if you want some really high end A3+ papers from Hahnemuehle, those cost almost 200€ for 25 pack, and you cant get smaller packs, and A4 sizes cost like 75€ for pack of 25, so if you want one type of A3+ paper and two types of A4 papers, thats already 350€, and extra set of inks like 120€, then you might first want some sample pack, and with posts, you are looking at around 500€ besides the printer itself. Ofc you could get cheaper papers, but inks being so expensive, it feels like waste of ink to use cheap papers, also if you just want A4 prints on cheap paper, they dont cost too much from print services, unlike fine art prints, especially larger like A3+ size. If you want A2 or larger prints, then you could use a print service, even if you got your own printer, but if you just want large prints, well then the printer will also cost more, and unless you sell the prints, it could be better to just use printing service. Printers need to be used from time to time, or they use inks to clean and lubricate the machine (or inks might dry up and wreak havoc in the printer). Ofc to save oney, you could cut larger sheets to smaller ones, but if you get A3+, and not A3, cutting it in half wont make it A4 size. But if you get A4 papers, they are easy to cut to A5 or A6 if you want smaller pics. Also for more random prints, it can be a good idea to get a bit cheaper paper. Like if you want to print anything half decent as small pics, then best ones in larger.

Even if you use external print service, you should soft proof your photos, which requires calibrated monitor and ICC profile, some places do however do these adjustments for money, not sure if some have some automated systems to adjust images, either way then you are not in control of how the final image looks like. Personally i think editing for screen is just the first step, sort of like pre-edits and print is the final image if im going to print.

I think having prints definitely adds to the whole photography experience and im sure people would get more out of their hobby if printing was more common, from shop or from your own printer, doesent really matter, but if printing a lot, especially on fine art papers, your own printer will pay for itself quite fast.

IMHO, convenience is the biggest factor.

Want to make a print during a party, to give to your guests? Want to make multiple variations of a print to get it exactly right? Want to make a birthday card the morning before you have to go to a birthday party?

Also, at least for me, having my own printer means I make more prints. My (Epson R3000) actually died two years ago, and I haven't really made any prints since.

Speaking for myself personally, while there's a part of me who would love to have a photo printer "just to have", I don't want to have to find space for it or worry about running it often enough to keep the ink and heads from going dry.

My most commonly printed size is 12x18 and my favorite paper to use is Hahnemühle Photo Rag Metallic. I can get that printed for $22 with free FedEx shipping.

If I was going to buy a printer I'd get the Canon Pro-1000 ($999) so I could print things larger as I need them. Unfortunately it doesn't take roll paper so I'd have to get 11x17 (Photo Rag Metallic, 25 sheets), which is $120 at B&H. So my initial price would be $45 per print. Obviously the more you print the less the cost will be, spiking again when you have to replace the ink ($699 for the Pro-1000). I'd have to seriously ramp up the amount of prints that I was making (and ideally selling) to make it worth it.

Using the lab gives me an easier way to experiment with different paper types and, recently, I've been having prints done on coated aluminum which is just beyond amazing looking. I've gotten a few 24x36 metal prints done for $300 each which is expensive but beyond awesome to look at. (Not that owning a printer would stop me from getting these, but I'm be less inclined to want to print on paper vs these kinds of prints now.)