What is the amps of the bilge pump. I know its 12V DC but to find a power sorce to run it from you house you need to know how many amps it uses.
At the very least you could run it off you car battery... altho that has its problems too. Possible to run an extention cord to you car? just cut off the male end and put a male end on it that fits your lighter socket. you could (for cost cutting) just wire the cut-off male end to your bilge pump, but its not recommended. You know the temtation to plug into the wall then..
If you are unfamillar with electricity then maybe you could find a friend to help you with wire thing.
Another possibility is to goto Wal-Mart and buy a yard tractor battery (around $25 with no old one) and hook it up to your builge pump. Of course then you have to recharge the battery..... So that seems to be a few answers hope that helps.