<p>I have the same experience - almost exclusively medium format for years. I have the 12 - 40 2.8 which I think is exceptional. I have ordered, and will have in hand tomorrow, the 40 - 150 2.8. Neither meets your cost criteria, but may be worth considering. The reason I don't use primes is because I shoot a lot of moving water in mountain streams. Sometimes there is only one vantage point so the zooms are very handy. I also have the Lumix 20mm 1.7 which I use as a walk-around lens on an EM-10. It is also very good. I'm going to be taking a six-week trip through the Canadian Maritime provinces later in the summer, and hope to use all three extensively.</p>