I load my Minolta 16/Kiev 30/303 cassettes three ways: cut a roll of 120 down to 127 and keep the strip left over; it's long enough (barely) for two standard Minolta loads (a little short for the longer loads standard in Kiev 30 and 303, 30 exposures instead of 20). If you don't shoot 127, it's easy to build or buy a slitter that can get
four 15.5mm strips (close enough) out of a 120 roll -- that's
eight reloads. Or, I find sellers who offer 16mm single perf in camera rolls (for 16mm cameras, that's only 100 feet). Foma 100R comes in this length, for certain, and I think I've seen Freestyle and B&H offering other stocks in 16mm single perf. Load the perforations toward the cassette bridge, keep track of which side the emulsion is on, and a couple feet will cover even a Kiev 30/303. Or I find 16mm microfilm, which is typically unperfed (works fine in Minolta format cameras and many others) and comes in 50 or 100 foot rolls.
Now, FPP offers a slightly easier option, as their
Minolta 16 film is sold in
25 foot lengths, two color (repurposed cine) and two B&W (also repurposed cine, it seems, since they recommend D96 for the ISO 20 and XX is clearly the standard Kodak cine stock). At their price, a reload for an actual Minolta (20 exposures, 16-18 inches) ought to cost less than two dollars for the film. If that's too much, buy a longer camera roll of 16mm single perf cine film (or, for the 10x14 frame, double perf or Double 8, which is 16mm wide and perfed both side, intended to be slit after development).
Freestyle has Foma 100R in 10m (Double 8 and Double Super 8 -- perfectly usable in a Minolta with 10x14 frame) and 16mm Foma 100R and Tri-X Reversal in 100 foot rolls.
So no, you don't have to buy four hundred feet -- worst case, to get below a couple bucks a reload, you have to buy 100 feet. Doesn't take up a huge amount of space (in your darkroom, fridge, or freezer). Not a huge problem to cut down to length.
The only reason I don't use my Minolta/Kiev 16mm cameras much any more is that I've gotten addicted to
big negatives. Put me back in a situation where I need smaller cameras again, and I'll be right back to the small film.