it's too late to sell it now. the 3g iphone will be announced tomorrow and chances are it will only cost $200 after subsidy. I mean you could probably get 100 for it if you wanted. but if you really wanted to sell it you should have done it last week cause you could have gotten anywhere up to 350 for it.
so it depends on your mom. i would never give an iphone to my mom because she wouldn't have a clue how to use it and/or want to use it. she has an old nokia block phone and she keeps it off, only turning it on when she makes a call. she has 3 numbers programed in her phone and I had to do all 3 of them... soo yea...
so unless your mom would make use of it, i'd advise taking it apart! if you know what you are doing that could be really fun!