I'm sorry, I don't know much about artillery, but I did recently see an m1938 (M30) 122mm Howitzer for sale for $6,600. I know it is a different weapon from yours, but I hope this helps some!
Looks to be a pretty good condition demilled Russian Model 1910/30 122mm howitzer. These cannons were originally manufactured in 1910 and used in World War 1. In the late 1920's, they began modernizing them. The bulk of these howitzers were modernized in 1930, thus the model name.
It's in pretty good condition. I'd estimate that you could probably get anywhere from $6k to $10k out of it from the right collector. You might try contacting these folks listed below and see what they think about it: index
They buy and sell quite a few old mortars and howitzers. Maybe they will cut you a good price.