Anytihng that is halfway decent with the ability to do multiple inputs is going to be expensive. I use 2 x MOTU 828 mk II and that gives me (with out using the ADAT inputs) 24 simultaneous ins at 24/96. However as far as expense goes that is not the real killer. Mics, pre-amps, cables and most importantly a good monitoring system will knock a real hole in your budget. I the pres on my Peavey desk for things like drum mikes and for monitoring Pods however I still have two better than average mic pres that I use for vocals.

If you are on a sub-thousand dollar budget, you might want to have a look at a second hand Korg D1200 / D1600. These will come in at between 4-600 USD on eBay and are great bang for your buck. They are portable and you can also export tracks from them to a computer to mix and edit at a later date.

These machines will give you either 4 or 8 simultaneous input respectavley. And because they will not break the bank you can also think about some microphones.