Just give it to him already. Ask him to pay shipping, and bask in the good deed while you wait for your new machine. Rather than asking him to part with a small amount of money he probably can't really afford and you likely don't really need, tell him to pass the favor on to someone else someday.
This actually came at a crappy time for me, since right now I don't have a lot of disposable income - I'm 17 and jobless (no available transportation...). I would try to pay at least $100 or something, but right now I'm almost flat broke.
If you're okay with going total charity, you can email me at tommy04@gmail.com so we can work it out, but if you're not, I understand.
It's a generous offer in either case, and I didn't mean to imply otherwise. I just wanted to point out that without some price guidance, it can awkward telling someone how much you can afford to pay for fear that they will consider the low number insulting. I think explicitly telling him that you will do it for free but asking for money if he can afford it is a great compromise. Good on you!
I want to buy a new one to run OpenCyc (which requires 4gb) on but I can't bring myself to just scrap the old one.