How often does this occur?

I need to have my BCM repaired and saw on xemodex that they also rebuild the pumps.

I was thinking if I'm taking it apart it might just be worth it to have it done as well.
I don't see many people posting with pump issues but at the same time I don't want to
spend $500 to have my BCM repaired then have to turn around in a year and spend $750
to have both done.

Is it something I should consider or should I just stick with having only the BCM repaired?

 

Its not a common fault but it does happen. I had the ABS pump go on my 850 and simply wound up getting a used part for a fraction of the cost of a new part. That "used" part lasted another 10+ years. Keep in mind there's three parts in play 1) the pump 2) the BCM (the valves) and 3) the ABS controller board. When you buy a replacement, for the most part you'll be sold the pump and the BCM as a unit. Which part needs replacing really depends on what your symptoms are. When I had a rear brake lock up issue on my S40, I bought a used ABS control unit with the valve unit for $60. Good to go and now I have a spare control unit.