There are this who say your support hand should never even be near the barrel, but it not like you are going be running HE rounds in it. Doing a quick search I see someone offering $200. for one. When they hit $300.00 I'll sell mine.
Troy made there EM203 grip for a short time, and thats the one I really wanted, but they dried right up.
Don't even get started looking for a Spuhr SLSM, as when they do come available they are stupidly priced.
One of the better bargins IMHO as far as M203 gear is the Matbock Aqiur Read Deploy Sight
https://www.matbock.com/collections/accessories/products/ard-sight