I went to my local VX dealer to look for a stand in so my omega can be returned to summer use and when the sales staff found out I had an omega they asked how much I wanted for her several times and with some enthusiasm.
It's a bit of an odd position to be in but just like people asking about her at petrol stations etc, welcome to the world of omega
Aaaaaand there's your clue.
...and in case you missed it - they want to sell you a new car!
If they genuinely wanted an Omega they could go on ebay and buy one for 50p 
It's a CD.........4035p.
Fixed... it's silver 
As close to reality as the £1000 valuation mentioned earlier.
My silver, CD spec Omega - once well known on the forum - was a 2.5v6 with LPG. Elite alloys, Bilstein shocks, polybushes, elite leather / heated / memory interior, huge amount of history etc. It was up for sale for a couple of months and eventually sold for £360.
It was heartbreaking to sell it for that after all the work that went into it, but as always, they are worth what someone will pay for them.
Imo, the absolute top price for any Omega now would be 2 grand, and it would have to be a really good example coupled with a keen buyer.