You can get what you need from PBC Linear.... give them a call at 1-800-962-8979
whenever I call, I usually ask for an application engineer. the last time I called, I spoke with "dave" and he was really great. If you tell him what you want, he can verbally tell you what each component costs so that you know approx what your total will be and what size bearing to order.
And since PBC makes their own bearings, you can be sure that what you get from them today, you'll be able to get from them years down the road.
p.s. Grainger and McMaster sell PBC bearings... but you pay a premium for them. There may be others, but Í know I've seen their stuff in both of those catalogs. (grainger does seem really high)