welcome. nice p5 like the blue. if your not familiar with this car, it has been very reliable in my experience.
a few things to watch for is the h7 headlights tend to not last long if you drive at night a decent amount, the coil packs are notorious for failure (obvious when they do) but are relatively cheap and easy to replace. have the timing belt checked(or just go ahead and replace it unless your 100% its been replaced at the correct mileage, and its not near time again)
a good idea (as i do with all used cars) is seafoam it. basically go get a bottle of seafoam and start your car up, get it warm (so right after you get home from buying is good) shut it off, disconnect the brake booster vacuum hose and crank it up(it will idle bad while doing this), while its idling slowly pour in about 1/3 to 1/2 the can (slow enough so it wont die) and then cut it off and let it sit for 5-30 minutes. then go drive it (it will smoke but thats fine) drive for awhile and after enjoy your freshly cleaned engine egr and exhaust system