New Set Of Wheels

I would love to have the office one step closer to "finished" and I believe the next step is figuring out the chair situation.  The reupholstered cushions came in but I want to have them sprayed and use them as the desk chairs.  The problem is they are not tall enough for the desks and I really love a desk chair on wheels.  

 I thought adding casters would be easy but the base of the legs does not allow anything to be screwed in from the bottom and the tapered legs add another difficult element.

One solution is casters made for antique chairs with cups that cater to the tapered legs but so far all that I have found have been at least $13/caster like these.

However, I am unsure of these are made for heavy use and when you multiply them by 4 legs on multiple chairs- chairs that I love but not worth spending too much on- it becomes more than I want to put into these particular chairs.  So, if you know of any options I am not thinking of for these legs please let me know.  I would love to be able to use the chairs if possible.