Yeah i think it is i think it is due to demand the serise has due to it's exposure again.
You can thank in part for mega man 9&10 coming out as down loads for the PS3,360 and wii.
Heck i've seen people interested in mm 1-6 all of the sudden...ever since 9&10 have came out.
Only two of my ~40 SFC games are CIB (Chrono Trigger and Umihara Kawase, plus I have just the box for SFII and just the manual for Ranma 1/2 Chougi Ranbu Hen). I usually don't care in the least, as Super Famicom boxes were kind of crappy anyway (though it's nice that they're video-sized), and if you want to play the games, you'll probably find yourself storing the games and boxes separately anyway.
I wish I had the manuals for more games though.
Anyway, for disc games and games for systems with durable packaging (like Megadrive and Nintendo DS) where the boxes tend to survive and to be used, I can totally understand insisting on CIB. Otherwise, it depends on your motivations for owning the games, I suppose.
Yeah, it's usually up at around $100-130.
I lived in Japan when I bought it, and IIRC, it was around 7000 yen-ish (so about US$70). That was CIB with a strategy guide, but yeah, it's probably the most expensive SFC game I've ever bought. Clock Tower would be second - that was loose, but it was more than $50.