Just got off the phone with Century BMW Greenville, SC. Here is their over the phone quote for my pre-owned '06' E53 31,000 miles, original warranty good till 2/10.
Warranty 48 mon/50k = $4,295
Maintenance 24 mon/50k = $2,895
Think I'll pass and bank the money for repairs since I only drive it about 10k/yr and it is in great shape now. Also it is a no frills model, less stuff to go bad. I'll take my chances.