Value of a Vintage Eaton Viking Ride-on Lawn Mower?

The actual price you can sell a lawnmower like this greatly depends on the condition of the mower. Some people will buy one that is not working to restore the mower and others will buy it for parts. You did not say if your mower is working or not.

If it isn't working then the price you can get for the mower is a lot less than if it is restored and in working condition. If you could tell us more about the mower it would help us to determine the value of the mower.

Lawn mowers cannot usually be shipped so the area where it is located will determine the actual resale value. Some areas may have interested parties while others wouldn't take a second glance.
Your pictures are not really good enough to post to any forum for help as you need a couple close ups of the full machine as well as condition - running? ever had it running?

Most forum will not tell you anything about value as they are more interested in what people are doing or needing to do to restore these mowers. They are not into giving appraisals but may mention that a similar one sold somewhere for a certain amount which is of no value to you unless it was in your neighborhood.

Have you tried placing it on your driveway with a for sale sign?
Sometimes this will tell you if anyone is even remotely interested in this type of mower as very few older mowers are considered 'collectible' so it would have to be someone who wishes to restore and use the mower.
As to price; start it anywhere you like - even $75 - $200. Anyone interested will let you know quickly if that is too much money.

Place ads in Craigslist, Facebook Marketplace, OfferUp, USA for sale (your area) and place good pictures with pick up only.

Start prices like above and lower as necessary.

If it is not your mower and your're thinking about buying;
Running? $75 with usable tires (tires are very expensive) or $50 if you think you can get it running for only a part or two (need new carburetor? never!).
I'm being realistic but others may think differently. I live in Florida and occasionally someone will list one of these for sale - usually $75 - do not always sell.
Eaton Viking is not a well known brand an many people might wonder if they could find parts when needed.

The following site is registered in the UK.
You can ask questions about this mower such as finding parts or year produced but no questions about value on this site: I think you have to become a member.

www.oldlawnmowerclub.co.uk/forum

You may be able get more information from this site and they have a section of classified ads.

www.atltf.com/t5920-my-eaton-viking-drag-mower

www.yesterdaystractors.com/.../wwwboard1.html