Personally i can justify some of the high prices for replacement cases to some of the absolutely rare games, like, even if i'm not going to sell them, it was still cheaper for me to buy a replacement case/manual to my loose copy, than it would be to just buy a cib copy, and i find that generic cases are a good way to just get your discs cracked(rip that copy of conker i used to own, hope it's in a better place and didn't shatter in an xbox)
tg16 stuff is weird though, i've seen the regular cases go for $10 or less, yet the repro stuff that requires you to buy your own stickers, and i think CD cases is 8 dollars each.