The going rate for a USED 551 is more than $300. Even used 511s go for $300. On forums I think $350 for a used 551 is pretty standard. On ebay they're going for ~400+. If you're comfortable with the seller and what he's selling I wouldn't hesitate to get a NIB 551 for $300.What's the going price of an Eotech 551 I have found one for $300. I really want to add an eotech to my AR. The 551 is new in box and is not a clone.