As guitarboi said, if you're planning on selling CDs, and oyu're going to put a lot of money into this, then I'd suggest multitracking- even if you multitrack "groups"
(ie, group the drums together, mix them on site, and record them as one track)
That way you don't have to mix so much later.
The main advantagte to multitracking is that if something doesn't sound right, you can just re-record that bit. But if you just reacord the mix, and someone hits a bum note, then you've got to re-record the whole thing.
Advantages of recording a mix straight up are pretty much as you said- it takes less time.
My advice on what to buy? Probably an 8-way pre/ADA, like the Firepod, or onyx 1200F (when they hit the market). They're not going to break the budget, but they will get sound into your computer at a relativley high quality.
I'd also get some monitors, that would be a big bit of the budget right there.
Maybe a few compressors etc, like the RNC mentioned above, and some decent pres- better than the ones you'll find in your mixer (however, if you mixer is something like
a Heritage 3000, you probably won't need new outboard pres).
I'd also look into things like the UAD-1 sound processing unit- it's a PCI card that is designed soley for processing audio in the box.
maybe some decent mics if you haven't really got any good ones- pick things that are goign to be generic, like a few sdcs, a couple of LDCs for vox etc, maybe a few dynamics for the drum kit (for specifics on mics, check out hte "microphones" forum).
As for spending 75% of your time... well, that makes it an obsession... don't get trapped by it (it's hard to escape... i've stopped trying).
As for making money... best of luck. I can almost garuntee you that there will be times that you'll be eating rice becuase of lack of funds. But then that gig comes in and you're rich again...
Selling CDs is a problem in itself. People can tell the difference between a good CD and a bad one, and the whole "mastering" process is far beyond most HomeReccers. Sure, you can run a limiter over your tracks, and burn it to a CD, but it won't sound like something you'd pick up of your music store's shelf. In the beginning, I'd reccommend that you get someone else to master your mixes. It costs a bit, but if you're trying ot sell CDs, I strongly reccommned it. There are a few mastering houses represented on these boards, jsut ask around and you're bound to run into at lesat one of them.
Oh, yeah, and those questions were more rethorical, in order to get you to think about your situation and work out what you needed... but no harm done...