I own 4 non-metered Ms and use them all regularly: the M2/M3/M4/M4-P. Of these, I'd start with the M4-P because you can obtain them at a price point within your budget and they give you the versatility of all the framelines in the VF from 28 to 135. The earlier brass top models have the more accurate 50mm framelines that the later M6/M7/MP (not MP-3) don't have. The M4-P is a workhorse camera and I have grown to love mine.