Charter Arms Pathfinder is a good one and then there's an S&W 351PD. It's expensive and it's a .22 mag. The mag is still a lot cheaper than centerfire but gives more sound and blast which would make it better for training. The have a similar gun in .22 which is their model 317 Kit gun. It's an excellent back packing gun. The Smith's are very expensive and not too practical in my opinion. Not good for hunting, no good for CCW, not suitable for a woods/hiking gun because of the first two negatives.
A little cheaper and perhaps a bit better than the Charter Arms is the Taurus ULTRA-LITE MODEL 94.
Any of those should give you practice on the trigger because they're all heavy and the Taurus and Charters tend to be gritty as well but smooth out a bit over the years.
If you can find one used that would be ideal but they don't normally show up used.
Only other down fall (already mentioned) is the in ability to practice reloading which is one of the main things we need to practice with a revolver. For that a bunch of dummy rounds in speed strips or speed loaders is ideal.
Another way to train with the revolver and save a bit is to buy wad cutters by the 1000 from someone like Georgia Arms.