If you want to save money then follow the advice of ACCSYS. If you want the EXPERIENCE of eating lobster then hit one of the roadside restaurants with outdoor seating. Get fries and slaw to go with it. You can't go wrong with MOST of them. I don't know what other towns you might be in but I would NOT go to Ogunquit Lobster Pound. Our last couple of visits were not good.
DISCLAIMER: I do not eat lobster but I am the only one in the family who does not. The above recommendations are based on family input!