Pete,
you ask a good question, there is no magic formula I've discovered but I think it's fair to say it's the ladies that do they buying. So I make decorative items, things that can be displayed, lots of different coloured items (to try and fit in with any room colour scheme), they don't normally have a use except look good. Think of my coloured vases etc., I've posted pics of previously.
I then fit in the 'pick-me-up items, wooden fruit, some pendants, small boxes and mushrooms (why the sell I've no idea) but I try to make them from garden shrub trimmings. The seem to like to know they are something different, Burberis, Lilac, Buddlia, Mahonia etc., anything strange.
Another thing I've started (because the wife got into it) is needlecraft and lacework tools. Lace bobbins in real special woods, tatting hooks, pin-pushes, very large buttons, orifice hooks, craft irons etc., etc., they are small, so take up little room but can command a price well above their production cost.
Because I make these I get asked to make commission needlecraft items, today I picked up orders for a French Knitting Frame (like the little dolly thing but a lot more pins) and a Fair Isle knitting frame (to keep all the different colored wools separate).
One thing I don't carry is bowls, well maybe the occasional one, knitting bowls go well.