Nature of the beast, with selling used firearms. Any LGS is going to charge you at least around 15% to consign a firearm around here. More if they run it on GB, GA, and GI, as well as offer shipping.
I don't know what you were putting in for a reserve price, but I just priced selling a rifle with a $5K reserve and GB only wanted $127 for a 14 day auction with 90 day relist. Estimated final value fee was $208 if it sold for the reserve price. If your at $200 just to list, your not realistic in your reserve price. You need to find a professional to appraise the rifle, and not attach any sentimental value to it.
Auction houses like Rock Island charge a premium because they put in the work to get you the most money possible for your rifle. They take professional pictures, put out a sales catalog, advertise nationwide, handle shipping, and make sure tax laws are fillowed, they should be compensated for their efforts. They are doing work on your behalf that you can't easily do on your own.
If Rock Island is able to sell your rifle for $3000 but you can only get $1500 somewhere else, then is a 25% commission worth it? I mean they just just put $750 more in your pocket. Probably at least $900 more by the time you pay commission or fees to an LGS or internet site.