There are domestic manufactures if LMB2008 can't deliver what you want. Which brings up a question you are a awfully concerned about stretch and other accuracy issues but what about your lead screws?
My issue with stretch is that I haven't figured out how to calculate it yet, so I don't know how much of an issue it is. I feel like I have dealt with the issue by going up a size on X and Y screws.
On domestic manufacturers: I will check on them again when I get closer, but in the past I couldn't find one that would give me a reasonable price on the screw with machined ends. I have seen people buy Nook screws and then try to figure out how to machine the ends themselves. I just want to order them with end machining. LMB2008 does this very easily and cheaply.

As far as accuracy of the screws, I know I don't have the budget for brand new double-nut ground screws throughout. That leaves me with C7 screws, particularly for the X, which require a pair of long ones.

I messed up and switched X and Y when talking about 2 glass slides. Here are some pix.
Two 63" ones on the X @ $409.90 each (later!): Attachment 192290

One 36" on the Y @ $239.90: Attachment 192292

One 14" on the Z @ $209.90: Attachment 192294

These are from ZS SYSTEMS - Digital Readouts (DRO) & Glass Grating Linear Scales

You can see that the cost to add these to the Y and Z is very reasonable! It is certainly far cheaper than the extra cost of ground screws. I'm not saying that these are as good or better than having ground screws because I haven't seen them in action. Most people are using only Mach3, and don't have this option. It seems like a no brainer to use a Kflop and these slides. I do have to figure out how to shield the one in the Z, and I would have to build covers over the X slides, as they are facing up. I also have an option of squeezing the Y slide between the rails, above the screw. This would be more accurate.

Err steppers still require proper sizing if you expect them to work correctly.
I had spent a lot of time researching steppers, and felt like I understood them. Motorcalcs.xls helped a lot. Servos are new to me, so I am starting over. On the mechanical side, I have to find drawings of pulleys and mounts, and figure out how to mount them. I also have to figure out what acceleration I want (something I should have already done), and what size motor will work for that. I'm actually looking forward to working with servos, although I hear that tuning can be a pain.