The felt weatherstriping is no longer availiable but Webasto has the rubber weatherstrip in their aftermarket division. I replaced mine on my 89 and the rubber works good. Since you have to remove the sunroof glass to replace the weatherstrip, now would be a good time to replace the lifter arms.
Webasto order desk: 1-800-860-7866
Starlite 6 gasket: S1286-D5010A or 51590-E-5010C-A
Lifter arms: S1289-W-300A (right side)
S1289-W-3001A (left side)
If I remember right the gasket was around $12 and the lifter arms were $9 and change.
Todd