you could try these people http://www.wilsonglass.com/
Where can I find gaskets which hold the glass in the aluminum frames of my shower? The gaskets I have are clear, and slide easily onto either side of the glass to center the glass in the aluminum frame. I only need about 12 feet to fix the shower stall. I do not know the brand of the stall but I have several good pieces to take to stores but haven't been able to find any replacement pieces.
Important note - I'm not a pro
Retired Defense Industry Engineer
Try searching for "Shower Glazing Vinyl". We tried searching for "gasket", "seal" but our searches all came back with the wrong stuff. Glazing Vinyl is the stuff and it's usually sold in 20 or 100 foot rolls. Make sure you measure the thickness of your glass and the depth/width of the channels within the door frame to get the right size. We're redoing a shower with clear seals and they always look gross. Most of what I have found is gray and will look MUCH better when we replace the old seals with the new ones.
Good luck if you haven't done this already!