Just make sure to inspect the car thoroughly. Buying CPO doesn't necessarily mean the dealer is being truthful about the car. Speaking from experience, I bought an E46 CPO from a BMW dealership and when I sold the car, I found out that the car was previously accidented. And I did have it inspected....
Make sure to get a vehicle history report. Most dealers use "carfax", but I would recommend using "autocheck.com". They appear to be more accurate with vehicle history!
'06 E90 330I // 6spd // M3 Style Full Body Kit // Simota CF CAI // 19'' Avant Garde M368 // Bilstein PSS9