My fiance had an emachine for a few years. If you know what you’re doing with computers, it’s not hard to find parts. I know that his major problem was that the one he had (this was quite a few years ago) used DDR RAM, and when he wanted to upgrade, SD had pretty much won the battle. That was his major reason for getting rid of the emachine, and he decided to build his own after that.
If you’re not all that computer-savvy, you might want to consider getting a computer from a retailer that offers a service plan.