if your need for cash is not immediate, it is worthwhile doing some research on the market. By using past auction results (there are many links on this site) you can estimate if prices realised at auctions are going up or down, you can then use your judgement in deciding when to sell.
There are many hidden costs when selling on eBay. Ebay's commission charge is in line with most auction houses, plus there is their listing cost and another charge from Paypal when you get paid.
You may think you get a wider audience on eBay, this may be the case, however that audience is general. Specialised buyers, those interested specifically in your antiques, cars etc go to auction houses. Why? Auction houses provide services that eBay does not provide, this is professional valuations, advice on reserve prices, incremental bidding, insurance etc. Your item is professional photographed and described in a way that will showcase its qualities. Auction houses are knowledgeable sellers who get serious buyers, and as result generally better prices. Many auction houses have on-line sales attracting customer from all over the planet. A buyer has a greater chance of getting a n accurate description, picture on an item et at a price that reflects its true value.
Lastly an auction house will have a select amount of items, the item your selling will not be lost in a sea of other entries,
Researching past sales results on items similar to yours will give you a guideline.Many auction house offer a valuation service, and most offer this service free. They will offer valuable advice on what reserve price you should set. The auctioneer has years of experience, a first hand knowledge of the market and a wealth of resources to use when advising you on a reserve
Almost all auction houses charge a commission for selling your item. There may well be a nominal insurance charge, and if your item does not sell and you do not collect it, a storage charge. generally the more specialised the auction the higher the commission rate. This is because the auction house will put in extra work to advertise your item to serious buyers in the are area that you are selling in, with results to match. A specialist auction house, as opposed to an auction house that only sells general items, will have highly qualified valuers who have a depth of knowledge in their speciality. This can often pay off, for instance if you put that antique car into your local general auction it will sell as best as that auctioneer can value it. But if you sell to an auction house that specialised in antique cars, they are more likely to know that car and give a more accurate reserve. Who knows, that old banger could be a rare special edition that is much sought after? That specialist auction house has more chance of knowing, its worth the extra cost.