A lot to be said for that, many wood carvers find old tools and customise them for their own purposes.
As well as eBay, what I would suggest is getting out to some country fairs and traction engine rallies, you often find people with large stands selling lots of old tools, especially axes and the like, that need a bit of work getting the edge back, and new handles fitted. Treefest at Westonbirt in Gloucestershire later in the year is ideal, there’s lots of woodcraft stuff there, many old tools, and Nic Westermann is always there, demoing forging, so it’s very informative watching him, and you can ask his advice on stuff as well.
Really worth looking on Google for events during the year, being able to actually handle the axe means you can judge if it’ll be too large, small, the wrong shape, etc.