If its used try to knock it down to at least $150. Thats what they run for when they are new. I bough a new mossberg 500 with an 18.5'' barrel and a 26'' barrel with a threaded choke for $219.99 at big 5 about a year ago.
If you cant get it for $175, walk away. it isnt worth more than that. Save up and get the 500.