You don't need a kit to build the cmoy. Tangent's and Cmoy's guides are both very good; Tangent even shows a nice component layout. Scrub the radioshack board well before soldering, though!
If you are comfortable with a more complex build, you can build a baseline Pimeta for that amount, too. No buffer stacking, basic op-amps, typical digikey parts, and the wallwart. If it works well, and sounds promising in your setup, you can swap in some nicer op-amps, or build a nicer power supply.
It seems to me that a lot of folks try to 'max out' their DIY project right from the start. That's okay, but it does increase the initial outlay. It will likely cost more if you go incrementally, but you can wash this out over time. Plus, it gives you an upgrade path without starting over.
A turnkey kit, with everything you need, would most likely run more than that budget. But if you have basic small tools on hand, you can buy a simple meter, plain-jane $10 soldering iron, a box of altoids, and the components for a Cmoy... all for about $60-$70. There is only about $25 in parts, but you always needs a few extra items if it's your first project.
There are a LOT of old threads regarding various 'first DIY amp' projects, usually accompanied by the subsequent debugging, but not always. It's very enlightening, and you can go through it vicariously through another's posts before setting out on your own. Look at the pics posted, etc. If there is a stumbling block, it's often common to many DIYers. Good luck.
