BMW Repair: 2000 323i automatic transmission ??, synthetic atf, 5hp19

Question
HEllo, the reverse gear on my 323i is slipping badly it still engages, and rolls backward however with any gas, it just free revs, local shop says transmission needs to be rebuilt the transmission is the ZF 5HP19 steptronic. is this the case? if so what costs could i face?
-Thank you,
Jon Calmes  

Answer
I woulf guess that the trans will need to be overhauled or replaced with a rebuilt.
The costs depends on a great many facters but you know its not good.
Min of $2500 with labor would be my guess.
There are companies that offer rebuilt units on Ebay.
I use full synthetic atf in my instead of the BMW fluid.  Works good and costs a lot less.