ABEC-7 608 roller-skate bearings cost 20¢ in the US, 40¢ here in Argentina, but are only rated for like 1-2 kN of static load. SKF rates their deep-groove 608 bearings at 1.37 kN static load. So what if you need more than twice that?
Well, you could support your shaft between three rollers at each end, and support each of the six rollers on two bearings. That ought to give you twice the load capacity: 4×1.37 kN. Also, it ought to give you lower friction if the shaft is smaller than the rollers and the rolling friction between the shaft and the rollers doesn’t itself contribute an overwhelming amount of friction.
If that isn’t sufficient, you can repeat the process recursively, by mounting a roller on your new shaft and making six such assemblies to support another shaft, containing 36 rollers of the smaller size and 72 skate bearings.
This is silly, though, because at the point that you’re spending US$15-30 on bearings, you might as well just buy a bigger bearing.