I'd be interested in it if it's not new price, but I'm a bit late to the party lol.
I bought a 250es with a cobra, and it sounds just fine to me, like just a tiny bit louder than stock. The DG on my 350x is loud as hell though, I don't get why cobra has the reputation of being stupid loud, maybe mine is just plugged up or the 250es one is just their quietest model?
Anyway, price wise, I suspect if you don't mind the wait, you could throw it on ebay for what you paid for it and list it as NOS and you'd eventually sell it with a 15% loss on ebay/paypal fees and shipping if you cover that on your side.
Just a couple listings to kind of see what the market is doing. On the cheaper end, nice looking exhaust but the guy has no clue what machine it's for, this is more my price range lol.
https://www.ebay.com/itm/Cobra-muffl...4AAOSwPvVcgXyV
On the other side, a clearly used exhaust for nearly double the price, but it's for a 3 wheeler.
https://www.ebay.com/itm/HONDA-ATC-1...EAAOSwFmtc0i4T
Here's a few sold listings, seems like the general price is $100-150, I saw one spike to $200 for an ATC70. None are actually new, just really good shape.
https://www.ebay.com/itm/Honda-ATC90...p2047675.l2557
https://www.ebay.com/itm/83-84-85-Ho...p2047675.l2557
https://www.ebay.com/itm/HONDA-ATC70...p2047675.l2557