Don't take this the wrong way, but have a read of Alex & Daves threads again they offer some very good advice and give you some excellent pointers, you may have had a quick response from them because they want it done for peanuts and can't keep a regular w/c all at the price they ask.
If you under price it you will just become another one of there statistics.
You'll become cheesed of every time you have to do it, put in a price you think will make it worth your while every time, if you get it at your price then thats great, if you don't get it at your price, chalk it up to experience.
Good luck what ever you decide.