Advice on purchasing vintage "tank" style?

Hi - thank you all so much in advance for your support - I have lurked here a little while and you seem to be an incredible community.

I very much love the sophisticated, slim tank or rectangle / square style vintage omegas and I'm getting ready to purchase one. This would be an everyday watch and an upgrade from my 1st watch, a Casio AQ230.

I believe I'm narrowing down my parameters - something small so the case is < 30mm long, white or gold dial, gold plated (due to budget), automatic or mechanical, 60s-80s. I see a few postings on ebay, some listed as De Ville and some Geneve:

1975 OMEGA De Ville

Omega Geneve Ref.511.415


My budget is up to $600. Do you think these are well-priced items? Do these types of watches come up often?

Thank you so much!!

Thanks for the reply. I haven’t seen anything that’s solid gold for under about $1000, which is more than I can justify spending. Am I wrong about that?