The $350ish cost includes.........
V-Glide Kit - Includes Precision Piston, Spring, Piston Seal, Spring Guide, Oil and Grease fits Weihrauch HW85, HW95, HW98. High Power. FAC.
"vortek and v mach are one in the same."
I tend to disagree in ignorance since I've never ponied up the coin for a V-Mach kit but I did buy one Vortex PG2 kit and made my own spring kit with a bare Vortek spring. Both springs sagged quickly with the PG2 kit losing 60fps shooting less than one case of CPLs (swapped out the kit at 4500 shots) and the spring kit I made up with a bare Vortek spring started dropping velocity at about 2500 shots. Matter of fact, both kits held nicely for 2500 shots before noticing a power drop off.
"outter spring guide/sleeve just like a vortek but cost more"
Looking at pics of some V-Mach kits it looks like the "metal sleeve" is simply a piston liner like HW supplies with their HW95 pistons. Also notice that this V-Mach kit has a metal guide and flange.
Here is a Vortek kit removed from a HW98 showing the "outer guide" which is integral with an inner guide and base flange.........
"Are we paying for the name or better quality? "
both, plus the V-Mach long standing reputation.
Concerning the cost:
I recently ordered some small parts from the UK for a HW97 and my HW95. Here is what I received for $58.50
Perhaps the fact that the V-Mach parts originating in the UK also has a bearing on the cost!