Looking For A Decent Outlet To Sell Valuable Coins.

Hey,
I own a LCS in Waterford, MI. I am young enough to be savey with computers and I use the store more as a location to purchase coins, bullion and jewelry rather than sell. Although I still sell all the above in store when customers are looking to buy, however I find it easier, safer, and more profitable to sell on ebay. While I still sell coins of all values on ebay, I am looking for a auction house that can reduce my fees for higher valued coins. I am a very honest and reputable dealer. I pay as close to true coin values and melts prices as I can. So close sometimes that even a 6.25% final value fee can turn a purchase in my store into a loss online. Rather then destroy my store's reputation by paying my customers less and risking going out of business like so many others have, I want to seek out other options. For example I just purchased 50 1928 st gaudens that ive gradually been sending into NGC a few at a time and coming back 65-66. As well as a few 1995-W proof anniversary eagle sets. I haven't had much time to research much but Great Collections seems like a great option. They seem to handle the entire load and when you have them sell higher valued coins, the Seller (myself) only pays a minor insertion fee of like $10, and the buyer pays the end price premium.
Any advice on Great Collections, or other websites/outlets would be greatly appreciated.