Are you buying or selling?
Selling? you should be able to get at least $35k
Buying? Anything under $35k is a good deal.
Unless you have a specific need for a RDIAS, ie you want to use on a custom lower so you can shoot pistol calibers, 308, etc...you might want to look into a RR, a non-colt RR can be had for under $20k. The difference can buy you a second MG