Are linear bearings overkill? I see they are $15 each in Mcmastercarr.
http://www.mcmaster.com/#6489k61/=4az5du
6489K61
Self-Aligning Linear Ball Bearing Closed, 1/4" Inside Diameter
In stock at $14.60 Each

Or cruise eBay, I've seen small ones for a fraction of this
price.

Karl