Welcome to the Forum. You have a 32 Safety Hammerless, Third Model, shipped very late in production for this model, around the mid-1920s. Your revolver is considered a modern firearm. You are correct that the mother-of-pearl stocks are uncommon, but yours are not factory original. All S&W pearl stocks had medallions in the top round. It was very common for distributors to add pearls to fill any orders that came in.
There were almost a quarter-million of this model made, so they are common. The value of these are quite low, not only due to the amount manufactured, but also due to the fact that many are found in next to new condition still today. Yours has some wear, but overall in good condition, so I would guess $250 if sold today.
One thing that needs to be addressed is the hinge pin. It is in backwards. The screw-head should be on the left side and there are small marks on the right frame and the pin that need to be lined up when properly assembled.
Actually, ammunition is currently available online from a few sources. Here is one that has it in stock.
32 S&W Ammo for Sale - AmmoToGo.com