Hi Blister
FWIW I've been keeping a fairly regular eye on Ebay over the last 6/8 weeks for s/hand lathes - about the only consistent element appears to be location! - i.e. if you live far enough away from large cities/conurbations not only will you get less light pollution, you'll also get (sometimes a lot) less for your lathe. Doesn't help by mail seldom being a practical delivery option!
Anything that has been modified will also attract less interest.
There is further confusion because some are sold with little or no 'extras', whilst others bundle 'extras' that are nominally worth more than the lathe - tricky.
As Russell says there are some that depreciate more rapidly than others, but they tend to be either the cheap/starter ones, or those with unfamiliar names. After that it becomes personal!
For a recognised brand, that's not their cheapest model, that appears to be in reasonable nick....here goes!.....I'd suggest you figure 60/70%. Separate any 'extras' from your calculations, mentally price them slightly less, and see what your overall total comes too.
Ebay sale values also suggests that ordinary s/hand chisels - no matter what make - will usually go for around half cost price, or slightly less.
Hope that helps
