Depends on where you live. I was in NY and that wouldn't have gone very far. Try out a few projects, and you can change it later as you feel more comfortable charging more. Figuring out what you're worth is pretty hard when you're starting out because it's easy to approach pricing based on what you would pay for the service your offering, than what the reasonable market price is, or even what $ value your client is getting out of what you're building them.

Also charging more for successive jobs wasn't a joke. You're being pretty transparent about your pricing; you could keep going and post how much each project cost and what the thing was that you built for that. Might make a more lasting marketing ploy.