May sell Boulevard, if so how much?

[BABYGIRLLYNDSEY]

I posted this once before and not sure where it went. Here is my question. I may sell one of my Britax Boulevard seats. I heard that you take the price you paid for the seat and divide it by 6 to get the cost per year of the seat. My seat was manufactured May 2006 and purchased September 2006. So, I am guessing that I would subtract one year cost of the seat. In addition to that, I was one of the ones that had their tether recalled by Britax. The seat is still able to be used according to Britax and I have a letter from them, but the tether would only be able to be used up to 50 pounds not 65 like the seat. I am sure this probably would affect the resale price of the seat. Does anyone have any idea what I should ask if I do sell? I paid $269 and don't want to give it away but would like some suggestions. I have the box, tags, registration card, manual, everything that came with the seat. Thanks!