I suggest you post your query on
www.singletrackworld.com. There are some owners of Jeff Jones bikes on there, and possibly a couple who have a Jones with a Rohloff. They will be better able to advise you on the potential sale value, and you would probably also find more potential buyers on that forum of such a niche bike.
I think the number of potential buyers of a Jones with a Rohloff is likely to be very small, simply because the overlap of people who like Jeff Jones bikes and people who like Rohloffs is relatively small. You might be lucky and have one or two people willing to pay a price that reflects the quality of your bike and the price of the build, as opposed to people wanting a bargain and only being willing to pay a low price.
If not, and if you only get very low offers, it might be worth selling the Rohloff separately from the bike. A Rohloff wheel on its own will have a much larger potential market. Similarly a Jones bike without a Rohloff will also appeal to more potential buyers. If you did not want to incur the cost of converting it to a 10 or 11 speed derailleur transmission simply to sell the bike, you could instead convert it to a singlespeed (something which is more common among Jeff Jones owners than using a Rohloff).
In your shoes, unless I absolutely needed the money, I would not sell it for a low price. If you regretted selling it, you would not be able to replace it readily later: current Jones frames use thru axles rather than the Rohloff friendly 135mm rear spacing. The frames are now also much more difficult to get hold of in the UK, because there is no distributor, and the prices are much higher than a few years ago, partly due to a worse exchange rate.
