Give him a break, he wants to get stuck in!
Spend whatever money you want to, but I would definitely suggest looking around first. If you want to just get stuck in and learn from your own mistakes - that's a great way to do it... It's just quite expensive if you buy the wrong gear.
Start with an M-Audio Delta1010LT soundcard. Find a mixer (im looking for one myself, so I can't help you with that), get some budget mikes (a few suggestions below), and plug it all into Cubase - this will sound shit at first, but you will learn why and fix as you go.
Microphones:
Assuming your band is the general rock set-up, you're gonna need to mic up a drumkit, guitar amps, bass amp, and record some vocals.
Drumkit - If your drums and room sound nice to your ears, just buy a Large Diaphragm Condenser and use that - it's not the pro way to do it, but there's no reason why you can't.
Guitars - The standard is the good old SM57, but I'd suggest splashing out a bit on an AKG C3000B, 'coz they ROCK on guitar amps.
Bass - Any dynamic mic with decent low end will do, or alternatively get a DI box and sod the amp - again, will sound like piss but it's a start.
Vocals - You know the LDC i told you buy? Use that with a home-made
popshield to record vocals.
I hope I've been some help, if not then I have at least stalled my boredom for a bit
