$800 sounds like a good amount to spend. How confident are you in your builder's advice? From my experience, in basements, the long wall is usually load bearing. In basements, room length is often not as much of a problem as width because of the load bearing walls, which are often at 13-14 ft. Several times, I received advice about putting in I-beams, etc. But that is often not as simple as it sounds. Many basements cannot adequately support the transfer of that much weight to the end supports. I consulted with architects who said I would be nuts to change the floor support. The costs for doing the job right were substantially higher than $800 in my situation.
If your situation allows that change for $800 and you can afford it, then I would go for it. My current basement has no interference and I love it.
If your situation allows that change for $800 and you can afford it, then I would go for it. My current basement has no interference and I love it.