Donating To Walks & Runs

I recently threw a friend a 20 spot for a walk she's doing. Not much, I know. But more than nothing. I have this "thing" I do. A couple friends walk and run and some stuff like that for charity. I've done a couple Komen 5Ks and other charity runs before. I'm not good at fundraising because I feel tacky and weird doing it. I'm just not one of those people who are good asking others to give me money - even if it is for something good like helping to find a cure for cancer or helping to feed the homeless.

How do I get the money to do this? I sell old junk on Ebay and keep a PayPal account. I use these funds to support friends ambitious efforts to do good. Things I've sold? Dresses I've worn to weddings, DVDs, books and other miscellaneous crap I have around the house that I don't need.