Hey Choptop,
If you've got those bubbles you can pretty much be assured there will be more of the tin worm work not visible until you get things apart. Probably inner and outer sills and doglegs. BN4's and BT7's are at the lower end of Healey values unless this is a tri carb which if it is a 1962 guessing it is. Those are of course worth more. As to your question, with the work needed to make it a driver quality car, Keith Martin's Sport Car Market price guide puts a tri carb BT7 in the low range of $35k and high range of $45k. If it has rust issues and been sitting for sometime and doesn't really run right now, I wouldn't pay more than low 20's at the most. Too many unknowns, what about your braking system, seals, hydraulics, etc and low 20's might even be high. Too many nice driver quality cars out there that might cost you more to get in but you will save money in the long run. As just about everybody will tell you, buy the best car you can afford where someone else has done the expensive and hard work.
Good luck,
Mike