Yes, I have sold a fairly large collection -- 100+ items -- through an auction house. More specifically, I sold through Rock Island. Was it worth it? Yes, I received almost a third more than I expected. I have worked in gun shops for almost 60 years now and have helped dozens of individuals, heirs, trusts, lawyers, museums, etc. sell collections big and small. In addition, as a collector and as one of those guys behind the counter at your LGS, I've been involved in buying from more than 40 different auction houses. Would I use Rock Island again today? Not necessarily... you have to remember that all auction houses do not operate the same.
1. All auction houses charge sellers different rates. Some auction houses don't charge sellers a percentage of sale at all.
2. Even if they don't charge a percentage on the sale, most auction houses will charge you to come pick up the collection, especially if it's a small collection. So, try to find a good one that is close or at least convenient for you to take your items to.
3. Many auction houses really don't like to spend time with low price items. For example, Rock Island has two types of auctions -- "local" or "regional" auctions for the lower priced, less collectible items, and "premier" auctions for the more valuable stuff. However, even with the more valuable items, Rock Island doesn't like to offer a single item if it isn't going to bring more than $1,000. From their perspective, such items are simply not worth the time. Other auction houses have different views on this subject.
4. The lenght of time involved has to be considered. Some auction houses will want to sell your collection at different auctions, which may be spread out over a year or more! You have to ask about time, i.e. will all items be sold at the same auction? How many auctions? How long will it take to get my money?
5. What happens if something doesn't sell? Non paying bidder? Etc.
6. Will the auction house allow a reserve? Some won't, some will but only with a charge to you the seller.
7. What about returned items? There is a chance, some say a growing chance, that somebody will buy one of your items and then return it because he/she isn't happey with it. They might contend that it was falsely represented (catalogues are another important question) or they bought it because they needed a few parts for a similar item they had and stripped the part off of yours and are now claiming it was broken, etc. What happens in those cases?
8. What about the catalog? Do sellers have to pay for pictures? Some auction houses used to do that; not sure any more. Paper catalog or only on-line? How many pictures? How many catalogs? How widely distributed. Listed on Proxibid? Auctionzip? Etc.
9. How many ways are bids accepted? Some auction houses are moving to "on-line only" auctions. The fewer ways that an auction house accepts bids, the more limited the number and type of bidder. Lots of folks will not bid on-line, but will submit an absentee bid either by phone or attend the auction in order to see and examine the item as well as bid in person.
10. Taxes! What do they do about taxes? Are you going to get a 1099?
Hope this helps some. Please keep us posted.