Structural problems

[Tim Anderson]

OK, so the house that I'm rehabbing has some floors that are uneven. Some are worse than others. It's made worse by the fact that there are baseboards from the boiler system still there to accentuate that there are issues. It's an older home (1937), so I'd expect some settling, but it's beyond that. The master bedroom upstairs is particularly bad. I was quoted over $3,000 to bring the upstairs master only to level. With this particular house, the numbers are going to end up being too tight for me to have work this costly done. My question is, are there any 'tricks of the trade' so to speak, to bring this floor to level on a budget? I've noticed the rooms that have tile in them(2 baths, kitchen) the sloping is either not present(doesn't make sense when it's noticable in all of the rooms without it), or the tile is doing a hell of a job in not making it noticeable.

I have a few questions here:

1) The dining room isn't completely level, would I be better off using tile or carpet? Can I even install tile on an uneven floor?
2) Can anything be done with the master bedroom upstairs, to bring the floor to a respectable level, without putting a ton of money into it?
3) I know that dark colors are a no-no when trying to sell a house, but would you go darker with paint/carpet to try to lessen the visual of the foundation issues? Or stick with antique white walls, white ceiling/trim and lighter carpet?

Any insight, as always, is very much appreciated.