When I had started consulting, and was trying to just stay busier with more jobs, I stumbled across a ifreelance.com post that was looking for a Drupal theme developer. I had built a few themes already, and felt I knew enough to tackle it. If I remember, the site's post was saying they were hoping it could be done for under 10k. If I remember right, my hourly rate at the time was around $40, so I was certain I could do it for less than that. I reached out to the job and asked if they had wireframes or mockups or anything that I could look at to make sure there wasn't something super gnarly. They sent me back the comps, and it looked pretty clean. Nothing crazy. So if I remember right, I put my bid in around 1500-2000, and was probably thinking I was overshooting it too.
Pretty soon after I put my bid in, I got an email back from them asking why my bid was so low. I ended up winning the gig because I was pretty straightforward with them that I thought they were offering way too much and it was a pretty simple layout. This contract ended up landing me my next 5 projects that would keep me busy for a couple years. I probably would've done it for free if I knew what they had in the pipe :)
Be careful that you don't price yourself too low, but also don't just bid 10k because that's what the ad said they were hoping to keep it under. That's what everyone did that I beat in that freelance bid.