Is it easy to sell custom built pc's?

I want to start making a profit off of my hobby. I've been building for 1.5 years, and I've built 4 rigs. The first was my own a gaming rig with a e8400 and a GTX 260 216 core, the next for my sister/her fiance, then for my mom, and a week after my mom's my sisters friend. I didn't charge for anyone because they were family and I enjoy building anyways (except my mom's... I reused some parts from dell, and I guess they don't like that). Would it be a good idea to start building a pc and selling it on craigslist or ebay? Let's say I put $800-$1000 down on a rig would I make $200-$500 profit? I really need cash as I'm doing drivers ed and need to get money for a car.

go look on ebay to get an idea of how much custom built pcs are going for, I have a feeling you wont be making much profit if any and wouldn't be worth spending your time on since most computer savvy people buy parts and non computer savvy people buy dells. Most ofthe peopleon this board has had that I should do this for a livinglight bulb go off toowhen they built they're first pc, I did, so I went to college and got my certifications and now have IT job with my own office which is where I'm typing this from lol.