If you mention to the potential buyer that it's your first pin, you may want to follow with something like- I understand it's as is and you don't owe me anything if it breaks down as soon as I get it home. I avoid selling to friends and other first time buyers because I just don't have the time to travel and help them fix it. Something WILL break. Probably soon, maybe the first day. If it's a reasonable distance I will help someone that bought a machine off of me, probably for free if it happens right away, but I can't be expected to do it.
I agree with the statement above looking for a deal. If you spend a couple hundred bucks extra and get game that a reputable seller went through and shopped, it's worth it. You don't need to get all of your money back every time either. If you sell in 6 months and take a $200 hit, no big deal. You rented a cool game for 6 months for $200.