Hi, Pamela. Go down to the thread "Painted over painted paneling" posted by Mary on 1/2/00. This will show some of the pitfalls with painting paneling.
Your question is difficult to answer because of the many types of paneling and the surface material that can be used. When I replaced paneling in our family room more than 10 years ago, prices ranged from $3 a sheet to more than $30 a sheet and I am sure that, with true exotic woods, the cost would be more like 10 times the higher figure. There is everything from vinyl wallpaper, to pictures of wood on mylar, to laminate-type plastics to real wood applied to the face of paneling. Some of these will take paint, some will take paint and it will flake off later and some will not take it at all. Tell us some more, Pamela, and we'll try to help. but I do have to say that, generally, painting paneling is not a good idea. If you have to fill the grooves, as in the referenced thread, caulk is not a good idea. Vinyl drywall "mud" is better but not perfect.