David:
Without knowing the item or the price, here's a few thoughts...
- As Ivan points out, ratings are only for completed deals, this deal was not completed so no rating is possible.
- When I buy something I want to be happy with the price but I also want the seller to be happy. Sometimes someone lists something at a price that is so low that it is obvious to me that they do not know the market. Rather that trying to hold them to their word on the price, I consider it the gentlemanly thing to do to let them know that they have under-priced the item.
In such cases, I will respond with something like this:
"Hi: I would like to buy the item you offered if you truly want to sell it at that price. However I do think you should definitely be asking for more money, if you look through the archives you will see that generally these go for about $200 more than the $450 you are asking."
Normally I get a response thanking me, sometimes the seller knows that the price is low and just wants to move the item, sometimes not. As I said, personally I want both a happy seller/happy buyer, I don't want someone finding out later that they could have gotten more.
I find this more commonly on Craigslist and other local ad marts. For example, last year I saw an 80mm WO Megrez II FD advertised locally for $450. This is the FLP-53 doublet with the two speed crayford etc, the seller had never used it because he hadn't bought a tripod. It came with a 2 inch diagonal which was extra.
I told the seller I thought he could probably get $650-$700 on Astromart, he was aware of Astromart and was comfortable selling me the scope for $450... He was happy, I was happy and I am still happy...

Just some thoughts here.
Jon