Sorry I've never looked at craiglist before but I seriously doubt it is a good representation of what most people are worth. These sites are generally people like you, desperate to get into the market, and willing do accept pretty much any price to do so. It'll end up doing you more harm than good.
You need to start by figuring out what YOU consider your time to actually be worth. Don't just say aww I'll just do it this time for $300 next time I'll make more. YOU WONT.
Get a figure and stick to it.
This figure will then be able to help you judge how much a project is worth based on how long you think it will take & your rate. DON'T BUDGE from your rate.
I know you need to start somewhere, but seriously, there are plenty of two bit programmers around. If you are quality, sell yourself as quality. If your not, then you need to get there first.