Modhouse T50RP MkIII Argons can be ordered (although there is a lead time) for under $500.
Dan Clark Audio Aeon 2 Noire (with EQ) scratches my itch.
EMU Teaks have great slam but don't extend as low into the sub-bass as the planars mentioned above.
I'm still trying to decide what's next on my basshead journey. I'm leaning towards the LCD-XC because EQ is not a problem and I've worn motorcycle helmets 3x as heavy so their weight shouldn't be an issue but always interested to hear what people recommend.