any suggestions for DIY seals?
<sigh> Yes, if you promise not to tell anyone I gave helpful advice toward the preservation of a diesel powered Benz
Go to Lowes, Target, Walmart, Ace Hardware, etc, and find black colored sealant, either the type for bathrooms, or any kind used where water is a factor. Using a small putty knife or an assistant, gently pull up the seal and put a small bead of the stuff as close to the end of the glass as possible such that when the seal goes back down, the sealant doesn't squeeze out and make a mess.
Gently press the seal to ensure the sealant mates the window to the seal. If any sealant squeezes out, don't worry - use a razor blade to scrape off excess.
You can do this outside the car, where getting access to the seal is easy, or inside the car where cleanup is more difficult, but the job easier to hide.
This is something I did with my 108, where the fix lasted literally years, until I replaced front and back seals as a matter of cosmetics (the dry rot was getting pretty advanced).
The best bet is to replace the seals and have done with it, but the cost of the seals ranges up to $500 for the two (and I'm being conservative) for OEM/OEM-quality, and whatever an installer charges per hour to do the job ($100 per is a good starting estimate).
Cost for a tube of sealant: $8 or so, plus your own time needed to accomplish the job.
I'll post another thread on how to check for a bad seal.