Since I don't make a living out of photography, I hold back buying a 2nd body until I have to (which is when the one at hand breaks down and is sent off for service) and then I buy whatever I can afford while the one at hand is being repaird.
Of course, it's easy for me to say that as I've got a few bodies hanging around the house ... but seriously, get the glass .... bodies, you'll always find one at a bargain. Just today I saw, at Jessops, a D80 body for £380!! It's their demo model .. what a bargain I thought, and it was hard to resist at that price.