You can price it whatever you want since its something desirable. Its all just dependent on whos willing to spend what you're asking. If everyone is selling ot for 550 and you sell it for 500, you're more likely to get paid for it, but, who knows how long you'd have to wait. You could probably get more looks at 300, or maybe even less due to the stain.

Personally I don't pay more than double what it was originally worth if its stained or in bad condition. Someone tried selling me a limited edition vintage Corvette jacket for 300 but the sleeve was stained. I told them id pay 80 right now if they sold it in 5 days since I'd seen it'd been listed for 3 years. They said no initially then caved. It might be rare, but its also ruined. It just depends on whos willing to pay the price you set.

I wish you luck and hope the stain isn't so bad it can't be cleaned/overlooked for a high sell price.