Actually you would pay much more than $500 for a decent Mac system. I would consider sending you my Mac when I upgrade only I don't have a Mac. I still have PCs running XP. Never had to reload it either. But when I do upgrade, I'm thinking seriously about getting a Mac. I was in the Apple store buying iPod stuff when I saw this incredible Mac system. Looked like a tank and had a huge monitor. It was about $3,000.
Hell, I have not yet spent even $1000 on my system(s).
I got my first machine from Dell in 2000 for about $800 and about the same time some guy at work bought a $2200 machine running at about 3 times the speed of mine and do you know how much his machine is worth today in relation to mine? There's not much of a difference.
Between the effect of Moore's Law, and the idea of buying into the new tech that has yet to be debugged the most economical choice is to buy 'second-hand' from the ones that think they need to buy a whole new system.
That's just my opinion.