Half of you seemed to say $100 was good for a US SSC. Now I'm gullible?
For a US card that isn't that bad of a price. The big picture though is that an Arcade Card + mod costs....about $100 total after shipping, which says something; people overpay for US stuff. Now, if you are talking about something like Cosmic Fantasy 2 (a text heavy RPG) I can see overpaying for a US copy when most of us don't speak Japanese. But AFAIK the only difference between a JP and US SSC are:
The words "PC Engine" are removed from the top of the screen.
Two pins on the card itself are reversed (so that it will work in a TG-16).
The instruction manual is in English...but you'll never need to read them because you just put the thing in and it works.
I did see a few 4-in-1s that had closed at $25 but they weren't complete (from what I could tell).
The 4-in-1 never had a back insert. Any back inserts you find are home made bootleg inkjet crap. The rest of the game is probably real though.
In the grand scheme of US hardware/software what you paid isn't that high. Some people actually do think that $100 for a US SSC is a good price. Personally, I think an entire Duo R for $140 is a good price.
I understand the thing about what your time is worth. That's why I stopped modding anything but my own systems. I used to do it for my friends for free, but as my daily schedule gets tighter I've lost interest. It especially sucks when you devote several hours to a project that ends up on eBay a month later because the guy got bored with it. However, if you work in the music hardware world than its just about impossible for you to not under understand the value of hacking the hardware!