well, i got a set/kit of curtains for my non-camper 88 bus from these folke:

Z-Products                     camper curtains, DIY camper interiors,
30625 S. W. Boones Ferry Road  camper pop-top replacement fabric &
Wilsonville, OR 97070          weather seals
(800) 331-9027
(503) 682-1267

but it was expensive: $140 for the pre-fabricated (i.e., all sewn up. i didn't
have to hit a lick on any sewing machines) curtains and the curtain rods and
instructions.  a very small amount of "modification" was needed to fit the
rear hatch upper curtain rod in place (the aluminum bar wasn't quite drilled
in the right place to use existing screws). no big deal.

one thought: i got light-colored fabric thinking that it would reflect the
sun, and thus keep more heat out. yeah, well ... what happens is that it
lets all the light through, and wakes you up anyway. :( just a thought.

you might also want to check with these guys:

Country Homes Campers       makes camper kits for vanagons/EV, which
493 Reynolds Circle         can be removed for weekday people hauling.
San Jose, CA  95112         pop-tops also.
(408) 441-6280
(408) 441-6282 FAX

Adventure Campers            Owner is Ed Anderson.
17851 Hwy 1                  They don't make VW's anymore, but sometimes
Ft. Bragg, CA 95437          has one or two older adventurewagens on the
(707) 964-4298               lot.
                                    art walker <ah@egret0.stanford.edu>

Sportsmobile
* 9805M Gray Blvd    * 5477M E. Hedges     * 250M Court
  Austin, TX 78758     Fresno, CA 93727      Huntington, IN 46750

they are alive and kicking and advertising every month in Motorhome mag.
send $2 for a comprehensive literature package with prices.
ad shows picture of first VW camper (1961). sources say they still make
straight-up pop-top.

and let's not forget: boat people have the same problems with windows ...
so if you know someone who makes/sells curtains for boats, you might be
able to find something that would fit.

i've seen some home-made curtains that weren't that much different from mine.
all it takes is an aluminum rod (or flat 1/2" wide strip) that is screwed
into the roof (after being bent out at each end, so the curtain can slide).
the bottom of the curtain can be held in place by just using "shock cord"
or elastic cord (usually sold at most craft stores). the only really tricky
part on mine is the little copper clasps that hold the shock cord in a loop
at each end. i suppose you could just tie a knot.

joel