1) Shure SM58 (not a condenser but used in studios thruout the world for recordings....) $99
What is a reasonable condenser I could use with that fairly cheap mixer?
Now that's funny. I personally think you can get a better sounding condenser for less cash than an SM58, and on the whole it'd be more flexible too. Just because SM58's are used in a lot of studios doesn't mean they're REALLY AMAZING like everyone will tell you, it means that when you have a clumsy drummer or vocalist or you've run out of good mics, you still have something dispensable left to put on an instrument that probably will be replaced when tracking. Just kidding, really, but I do hate these mics and everyones blind reliance on them.
Re: Behringer mixer, if you need a USB/Audio interface as well, you can probably get an audio interface which contains a couple of mic pres for not much more than this price. They will probably be comparable to, if not better than those in a Behringer desk, and in my opinion added "free" effects are a false economy as you may not use them, and you DO pay for them. Besides Logic has loads of better ones built in, and free good quality AU's are available online too.
You will need to connect a condenser mic to phantom power whether it's from a desk, and audio interface, or a phantom power supply, although some can run on batteries.
Whether you buy a desk or not, you will NEED an audio interface to connect a mic or other sound source to you mac.
Keep it simple and only spend money on the things you NEED.