The reverse clutch problem is the most common failure. We used to do a lot of reverse clutches when were were resealing the front pumps. Its only a little more labor than the complete front pump sealing.
We do not just do the clutches, when they go to failure. By that point clutch material is throughout the trans. The reason it failed was likely a failure of one of the 8 year old rubber seals. The problem with spending 1200 or so on the reverse failure is that 90% of the necessary 8 year old rubber seals will still be there waiting to fail in some other fashion.
The combined reasoning is why we don't just repair the reverse clutches once they have failed.
We do the whole tranny for about $1600 to $1800 (depending on damage) so the shop is in the ball park price wize.
Bosch Master, ASE Master, L1
33 years MB technician