I just bought a very good used 551.A65 with the cam operated quick release for $357 + 12 shipping. A very nice unit, is uses the smaller batteries. The AA batteries make it a little long for my taste. Sometimes EBAY is not a bad place to start. 8)
retail just recently got hiked from $399 to $419 on it. i can probably get you a very good deal, but all 3 of my distributors are out of stock on them, and EOTech is backordered from the factory on them....so, and in-stock ebay auction may be your best bet.