Odd color for Nesbitts, another OG post places it's use in the 60's. I'd not value it any higher than other Nesbitts faces that actually include the bottle. Average price was $250-325. If the odd blue color did add a premium price I'd still not think it would top that range by more than say 25%. If you look at Nesbitts performance on eBay, the signs don't get very expensive. Someone has a version of a clock asking for $600, but I think that's pie in the sky eBay marketing at it's best.
There are 2 versions of this color of Nesbitts clock. The difference is the tag line underneath the Nesbitts logo. I have the other version and it says "California Orange". The face has quality issues and think it is more of a $250 to $275 clock.
Always looking for back-lit advertising clocks, prefer Telechron, American Time & Electric Time. Also Pam in good condition.