My 740i is leaking brake fluid

[bwc740i]

I noticed a several drops of brake fluid on my driveway the other day. I checked my brake fluid reservior and noticed it was running low. I topped off the reservior and continued on with my day. After further investigation, I have concluded that I have a leak, but I am uncertain of the difficulty to repair this problem and what the potential cost might be.

I am a new owner living in the Arlington, VA area.

Your insight and help is appreciated.