A wall touches the ceiling, floor, and another wall - all of which will need to be blended, repaired, or replaced.
A wall contains electrical outlets and wiring, sometimes plumbing, and in my personal experience an old chimney (Surprise!!).
Opening up a wall is often worthwhile from an enjoyment aspect, and market appeal when it comes time to sell. It takes pros on site to estimate how the renovation will work out from a return on investment angle.
All the Best,
Jim Sweat, ABR, CRS, GRI, CDPE, e-PRO, ILHM
The removal of the wall itself can likely be done in a couple of hours if it's not a "load bearing" wall and doesn't involve electrical and plumbing rerouting. This shouldn't be too costly because you aren't involving any specifically trained tradesman.
Now once you have the wall out and you start tinkering with electricity, plumbing, dry walling, counters, etc. it can become more costly.
The fact that we have no idea of the configuration of your room and what your specific plans may be prevents responders from being able to provide you with specific information you require.
Hope this is helpful,
Jen and Mark Bowman
Keller Williams Realty