yep, buying a mac that is still in warranty is good buy, always. because you gonna extend applecare no matter what / that means when it brokes down, they replace it. So selling your mac for decent prize is actualy doable. I do not have any financial data, but this fact along could prove it.
If you paid $1000 for a Mac I would expect to get at the very least $600 for it a year later. If you spent $1000 on a PC I would expect to get $400 for it a year later. I just threw away a PC that I bought for $900 10 years ago.