Omega beta21 advice

Hi everyone,

I’m considering buying this Omega Constellation Electroquartz ref. 196.005 / Beta 21 from a private seller.

The watch has a new battery and is reportedly running and keeping good time. No known recent service, and unfortunately there are no movement photos available. I asked for better in focus photos and confimration that also the date works correctly

I’d really appreciate your opinion on:
Does everything look correct/original for a 196.005?
How do you rate the condition of the case and its polishing?
Most importantly: what would you consider a sensible maximum price to offer, given the unknown service history and potential Beta 21 risks?

I’m particularly interested because I collect vintage watches representing the development of electronic/quartz technology and a beta 21 is a missing chapter in my story

Thanks in advance for any opinions, especially from Beta 21 owners or specialists!

More photos