There aren't any computer modules that can run on 87. Sorry. With the Superchip, you can only run 92+. I have the Hypertech, and can run with 89 if I need to, but using 93 gives me much better gas mileage (and performance) so the higher gas pays for itself. The other chips suck, so don't even consider them.
So, if you don't want to use higher octane at all, don't get a chip. IMHO, the Hypertech is better since it gives you the opportunity to use 89 if you absolutely need to.
BTW, I was using 89 anyway before the chip, as my engine pinged after installing the filtercharger and cat-back with 87. Thus, it's a no brainer: drink the good stuff, baby!