I finally took the plunge and purchased some "real" linear bearings. They were a bit pricy, but I figured that for this project, it would be worth it since this is going to be my production CNC machine. Thankyou Blue Collar Supply of Sacramento!
I can't believe how smoothly these things slide. I guess that is why they cost a fortune on eBay...
I also picked up the matching 3/4" ground and polished shafting for a surplus price of $2.00/lb. What a deal!
I met a machinist down the street who did an awesome job of machining and drilling the ends of the shafting for the mounts. Thanks Jason!
I have heard that people have trouble aligning the shafts so the bearings don't bind, but I just took my time and made sure that the measurements where precise and the holes were accurate. It helps having a machinists rule and an automatic center punch along with a couple of center drills to get things going.
I still need to get some more T-6 plate so I can fab up the cross pieces, but the mill is starting to take shape.
After a few quick measurements with my dial indicator, I found that the shafts are parallel to within .010! I think I can live with that.