I would be wary of charging significantly less than other photographers in the area, but this also depends on a lot of things (listed below). I have several friends who are professional photographers and some of their biggest pet peeves are MWCs (moms with cameras) and 'fauxtographers' because they usually offer incredibly cheap shoots, with extremely basic or cheaply done prints, and since the customers don't know any different, when the customer does find a 'good' photographer, they balk at the price because so-and-so's mother did them for a quarter of the price.
A lot of the fee depends on:
1 - Your knowledge. Do you shoot on Auto only? Do you know about the exposure triangle? Can you use Manual, Aperture priority, etc. on your camera? Do you know how to properly expose for various situations, to bracket (maybe), etc.?
2 - What equipment do you have. Do you have a dSLR with at least a few varied lenses? Do you have lights or even reflectors? Do you just use a point&shoot (no matter how expensive it was)? Do you know how to use the lenses you have to the best of their ability and yours?
3 - What sort of post-processing, if any, can you do? Do you use Photoshop or Lightroom or are you using Gimp, Corel Draw, Paint Shop Pro, etc? Do you know how to fully use those programs, including print settings to get the best prints?
4 - Where are you printing your photos? Are you taking them to Wal-mart, a pharmacy, or are you taking them to a proper print shop? Do you know what types of format you will need to print them?
What you may not understand is that the photographers charging $400 are actually "cheap" when you think of all the time, money, and overhead they need to cover just to take those pictures. I'm sure you know cameras are not cheap, and even lower-end dSLRs can cost a decent penny. Throw in a higher end dSLR and you're looking at a significant cost. Lenses, too, are very expensive. Keeping up-to-date with post-production software isn't cheap either, pirating it doesn't really look good in a business. And that's what these people are doing: it's their business; their livelihood. Someone coming in charging not even half what they charge (even if your quality is just as good as theirs), is neither fair nor ethical (in my opinion).
A really good site to learn about photography and photographers (and how much to charge) is the Digital Photography School forums. Excellent site
