Well then, I'm pretty sure you're shit out of luck. If it's any consolation, plenty of solid games (Blazing Lasers, Bonk's Adventure) can be had on eBay for anywhere from $5-15, so you won't exactly be breaking the bank here.
Out there somewhere (I'm sure I haven't the foggiest where), there's 4M GameBoy Color flashcarts attached to HuCards. It uses the same transfer program as for GB/C roms.
It's totally slick, if lo-tech (the cart is mounted to the Hu with big globs of hot glue), and works great.
So I, uh.. so I hear.
TG16/PCE stuff is pretty cheap and plentiful, though; it's a great time to collect forgotten favorites. I recommend Zipang -- Solomon's Key reworked with ancient Japanese iconography rather than the signs of the zodiac.
Beware that you won't be able to play Japanese PC Engine games on that unit. There are adaptors that will allow it, but they're scarce and so expensive these days that they really aren't worth it.