This sounds like a fun project so here goes. The doors in your case will basically have no structural value. It's sole purpose is for asthetics and to keep dust n nasties out. Make it as light and stiff as you can. Check out DAMA for acrylic mirrors, its half the weight of glass and a much safer option.
A 3 panel track system (2 panels for door, 1 panel for the mirror) will be easier to implement then a 2 panel system with a pocket mirror panel. You can choose to have 3 panels to fully close your wardrobe or 2 panels with the mirror panel hidden behind either one of the other 2 panels.
Buying off the shelve 3 track sliding mechanism will be both costly and bulky. for a DIY solution, go check out sliding window replacement nylon rollers and solid aluminium rods in the 4-6mm diameter range to suit the rollers. Extend the width of the base, top and both end boards so they protrude out to accommodate the total thickness of all 3 panels. You can route 3 channels on the base board protrusion and glue the aluminum rods into the channels. That will be your DIY 3 track.
The top will be a series of tongue and grooves acting as a guide for the panels. Since all the load is supported by the bottom rollers and track, the guides only need to be relatively smooth to minimise friction and wear. Many ways to accomplish this, smoothening the bare wood + candle wax, epoxy paint, embed nylon guides, 8-10mm bearings as guide rollers or cutting grooves in both the top guide board and panels then inserting a UHMWPE (plastic cutting board material) tongue at both ends of each panel. Secure it to the panel with screws for future dismantling.
Advantages of a 3 track rail solution:
1. Components cost way less then a top suspension system. (does 3 track slim profile mechanisms even exist?)
2. Cheap, common, easy to source parts and materials. (DIY heaven.)
3. In a 2 panel to close design, make the middle panel your mirror and you can slide it out without opening your wardrobe. (How cool is that?)
Last and most important is not the potential cost savings, but the satisfaction and pride from doing it yourself.