Grips for the Colt SAA will fit the Gaucho. I found some dealers making grips and selling them on Ebay. If you don't mind doing some minor fitting, can get some nice grips at a very reasonable price there. Got some plastic ivory ones with the old Colt design for less than $ 25.00. Had to fit them by sanding and drilling a hole for the pin. Took less than an hour, getting my tools out and taking my time to do the work slowly.
If purchasing a pair of aftermarket grips for the Gaucho...please be aware, grips that perfectly fit the case hardened model will not necessarily fit the stainless model...some fitting may be required...good luck on your quest..bluegrassstate..