Can you not just put the dolly underneath it by picking up each end and then putting a spacer on the dolly to keep the legs off the floor but upright?

No, because we need to tip it up on the end It has to be standing up on the skinny side (legs in the air) to get it in the bathroom, and then we'll need to lower it back down.

Consider hiring two professional movers that can safely maneuver the vanity to its new location.

I called around already. Moving companies have minimums, either time or price, which makes it unaffordable. I had two guys offer to do it on the side, but they still wanted $200 to move it, and that is without the protection of the company's insurance.

I would remove all the drawers as possible to help lighten. And use the floor dolly. Carefully do a lift/tilt onto the dolly. Do not just tip it over, leaving the whole of the tilt weight on just the two legs. If between you and another you can't manage a couple hundred pounds, maybe you have a friend or two that could be willing to help out.

Thanks, that's basically the plan so far... I am thinking of lifting it onto something so it has a folcrum basically. That way, when I tilt it onto the dolly, the legs are already off the floor and won't have the weight of the whole thing on them at an angle.