I've learned the hard way that if you're going to do something for free or bartering don't expect anything in return... If the favor is returned I'm greatful but I don't expect it... It's like lending a friend money...I only lend the person money if I know I can live without it because chances are they're borrowing the money because they don't have it to begin with...so if I get repaid great, otherwise I choose to give it away... same goes for goods/services.
Bartering doesn't seem to work because one person always fee's they're getting the short end of the stick... It's not always the case but it's very common. I've found that sometimes it's best to just pay for what you want and move forward!