OMEGA Seamaster Cosmic Silver Dial Automatic Men's Watch_849306

Hi all- I am looking at purchase a vintage Omega Seamaster Cosmic for a colleague. I am a long time Omega fan, but have never purchased a vintage watch before. I was trying to research the ref. number, but the listing on EBay only has a CL number of 849306, which I am not familiar with.

You can see the listing here: https://www.ebay.com/itm/286258511963

Can I get some help with if this is a solid watch to purchase, if pricing is fair, has anyone purchased from this vendor, etc.?

Thanks in advance!