check these folks out:
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 after you pay $130 for their curtain kit, you'll hate yourself. ;)
it's soooo simple to make the things (once you've seen how they did it).
the curtains you make just bigger than the windows (say, two inches longer
on the bottom and two inches longer on the top, and in two halves ... so
they meet in the middle). and the top "curtain rod" is just a piece of
aluminum "rod" ... about 1/16" thick by 1/2" wide, and ever-how-long-the
window-is-plus-two-inches-on-the-ends. for the bottom curtain rod, you
just get "shock cord" ... elastic cord ... from a marine supply (boats)
or a sewing supply store. the curtains have a "hem" in the top and bottom
which the curtain rod (top) and the shock cord (bottom) fit through. or
you can leave the bottom open ... and the shock cord will keep it pressed
against the window "sill".

the ends of the curtain rod are just held in with screws (at each end, with
a little "loop" of metal in the middle of the rod to hold it up. it helps
to bend the ends in a Z-shape so the rod is held off the bus insides
just a bit ... helps the curtain slide back and forth.

the ends of the shock cord and just held by a loop of cord, clamped or sewn
together, with a screw and washer through the loop.

like i said, you can pay $130 for the kit (which is ok. it's a good kit),
but you'll feel like you could have saved yourself a LOT of money. ;)

joel