Mozart Piano Concertos

I have Murray Perahia on Sony and is (IMHO) an excellent set of Mozart Piano Concertos.Check Amazon and listen to the samples.
The Ashkenazy set on the wonderful Decca label is available new on Ebay for $29, a total steal in IMHO for 10 cd's with playing also of the highest order (I will be buying that set also).

I haven't heard the sets mentioned by others, but I have greatly enjoyed the mid-price set from Phillips Duo, with Alfred Brendel, Neville Mariner and the Academy of St. Martins in the Fields. (4 discs, two volumes)

You might consider Geza Anda on the DG labeled. This boxed set has been remastered and the sound is pretty darn good. Some really captivating performances. Another would be Mitsiko Uchida and the English Chamber Orchestra on Phillips, though I really like her playing of Mozart piano works better than the concertos.

If you ever reach the point when you truly cherish the Mozart Piano Concertos, you might want to listen to those renditions I would consider the most magical---by the wonderful Clara Haskil.

I heartily second the Brendel recommendation, especially the Dutch pressings. Another great Mozartean was Alicia de Larrocha, who unfortunately passed away a few days ago. I will be having a memorial listening session very soon! She was a great lady as well, I was fortunate enough to work with her a couple of different times.