Please confirm Seamaster model

I THINK this is a ref 2551.80. Seller is asking $1100. I am offering $800. No box, papers or service history. Does it sound like a good deal?
Edit to add: The seller does not know what model it is. He said he thinks it is a 2562 which I am pretty sure it is not. He mentioned it is mid-size.

Yes, I can confirm it's a 2551.80
I have one too...

US$1100 is already a very good price if it's the genuine article. You do need to factor in the cost of a service as well, if the service history is unknown. As always, do your due diligence. Get more high quality photos to better ascertain condition and authenticity. Does the seller have good reviews? Walk away if you have any doubts whatsoever.

To be clear, this is a very commonly faked model, and the blurry, distant photos you posted are not enough for anyone to tell you whether it looks authentic or not.

I wouldn’t send the seller any money until I’d had a chance to see several high-quality close-up photos. If they can’t or won’t send some, I’d walk away—these are mass-produced, easy-to-find pieces and you can find one from a reputable dealer anytime you want (albeit at a higher price). Not worth the risk to save a few bucks.

Also, you’re probably aware (since you acknowledge “mid-sized”), but know that this watch is 36.25mm in diameter. Those of us who appreciate vintage proportions don’t mind, but most wearers accustomed to modern 42mm divers would find this watch to be very small—the 36.25 includes the bezel, so the actual dial is indeed quite tiny by today’s standards. Not a problem if you have a small wrist. But something to seriously consider if you’re unsure.

I’ve become a devotee of the third-gen divers—the first ones with ceramic bezels, and, at 41mm, the perfect size on a typical 6.5 - 7” wrist. They can commonly be had around $3k, fwiw. If you suspect you’ll end up tiring of the smaller piece you posted, then it could be worth saving up for one you’re bound to like more. Many of us here on the forum have bought watches that, in hindsight, we shouldn’t have—then paid to service them, only to end up selling them at a loss. It’s cheaper to wait and buy the watch you really want the first time.

To be clear, I like the 36mm divers and I have a 6.75” wrist. But it’s worth knowing in advance what you’re getting into. 😀