Technically, you probably are required to pull a permit, but some contractors may do it without one.
As for cost, alot depends on the type of floor that needs to be removed and how far you have to cut to get to the nearest drain line. If it is a concrete slab, you could be looking at some real bucks. You could easily spend $500 - $1500 on cutting, patching and replacing whatever floor cover you have. The plumbing cost would be fairly insignificant compared to the floor cutting.
Now if you have a wood floor that is elevated, that is a different story all together.
Louey