In some ways Yahoo is little different than ebay. The only notable difference is that there is not as much traffic in coin trading and the selection is smaller.
There are a few internet coin auction sites that all have similar attributes to EBAY. Each will differ in some of the finer points. Ebay just happens to be the largest. But with everything else in life, bigger isn't always better. Just as with buying the book before the coin, use the same philosophy with auction sites. Learn all you can about the coins, so that you may buy with confidence, no matter where they are offered for sale.
Also, BIN prices remain available after the bidding opens, and all Questions to Seller, with any responses, are publicly posted.
The more eyes that see your auction the better off you and your auction are going to be. By far E-Bay gives you the most bang for the buck.
Depends if you are buying or selling I think. I have had some luck selling on yahoo, but it seems most sellers asking prices are too high on their reserve and asking prices from what I have seen. But if you run across a reasonable price, you have less people bidding against you. Same rule as always..........have a price in mind and stick to it.