I have seen ball bearing full extension drawerslides being used before with good results. If you want an inexpensive pair, try any copier repair place. They usually have big machines in back that they are going to pitch. Look at the paper tray sides. I also saw one machine using garage door rails and guide wheels, I don't what kind of accuracy he had though.
I am still new at this but one thing that I found that works well is cabinet pockit door guides. They are self contaned and have a rail to mount Y support to. You can get them up to 28" which will give you about 24" of travel. The best ones that I found are the accuride brand. model CB123-28D Check with cabinet suppliers.
Milton