Daytona zenith el primero white advice needed

[Lmacaluso]

Hi guys,

Im new here, and learning step by step about the fantastic history of rolex, i would like to buy a third watches, i v been offer the daytona zenith el primero( see on the pic). I like the old vintage design, but i m not sure what its worth and how much i ahould negociate for it, i know its and old model and i need the to check the condition, what else should i check ? Is there differwnt model for the zenith white? Size ? Years ?
The seller dont get paper and boxes, but i have check it at the shop, everything seems fine, how much should i offer to get. Fair deal.

Thank you for yor help and sorry if i ask stupid question, i m the new kid on the block.

Appreciate the answer