I have been able to secure original equipment E9 rubber for all of the car, doors, trunk, windshield, windows, etc, etc. Email me for current prices at csilcoupe AT msn DOT com. For example the very expensive door seals which the last time I checked BMW is selling for nearly $500 PER SIDE I can supply for $330 per side, or $639 per pair. These are from Germany made by the company that supplies them to BMW and they resell as new OE parts. You are getting exactly what you would from BMW for at least 30% off, better than any dealer discount I know of.
Examples of current prices (2013), inquire for prices of other seals:
Door seals - the seal that mounts to the body's door frame and goes all the way around from the rear of the door window forward along the A pillar, across the bottom of the door opening and up what would be the B pillar on most cars. This is typically the single most needed seal on an unrestored car. BMWs price - $500 EACH , my price $330 per side.
Door Seal that mounts to the rear of the door - A rubber piece that is adhesive bonded to the rear edge of the door and seals against the door jam composed of two pieces bonded together, why BMW charges nearly $140 EACH for these is a mystery, mine are only $90 each.
Quarter window seals - runs along the front edge of the rear quarter window and attaches to the aluminum strip - only $25 each
Windshield and rear window seals - holds the glass in place, if these are allowed to rot away your dash wood will suffer and ultimately need replacement. Well worth the cost to change them out - $150 each
Trunk Seal - Water in your trunk rotting the plywood vinyl covered panels and rusting your spare tire well away, this should fix that problem - $130 from BMW last I checked, mine are only $99.
More available, email me for prices. Highest quality parts as sold by BMW