So the first thing that came to mind was one of those decade-resistance boxes for prototype circuits:
These are generally made up of multiple 1p10t rotary switches with 10 resistors (0,1,2,3,4...9) per decade. So you could get a 1p10t rotary switch and solder in 10 resistors corresponding to the 10 resistances you need. But these are 2-terminal widgets and not the 3-terminal potentiometer that you may (or may not?) need.
I figure what you're really after is the mechanical detents provided by the rotary switch. So how about modifying a 1p10t rotary switch by extending its shaft on the bottom end. Then couple this shaft with a collar to the shaft of "any" potentiometer.
It's just that while you may find a 10-detent potentiometer, I'd think these would be specialty items so spendy and with limited choices.
