The M-Audio Delta 1010 looks like a good value,
it gives you a 10 input soundcard, all line level, so if you want to use mics, then you'll need some mic preamps or a front-end mixer. I've seen the Delta 1010 for about $550.
M-Audio also makes smaller soundcard units than the Delta-1010, which would be less expensive, and feature a variety of versatile inputs. I've seen 'em, I just can't name 'em. I think one is
the M-Audio Delta-66. Check it out.
There's the Sea Sound Soloist, for $99 @GC, which is a hybrid sound card of sorts. Also, very similar, is the Sea Sound Solo EX, for $199 at Guitar Center, which is more full-featured. These boxes will interface mic or instrument signals into the PC, and are not that expensive.
Tascam makes an 8-input soundcard,
the PCI-822.
I'm sure there are other units that people will recommend.