Certainly the Planar is superb but the cost will run between $500 and $600 US. Take a look at the Cosina Voightlander Nokton if you want a fast lens, high performance, great build and a price of around $350 new. It's all brass with excellent construction, fast at f1.5 and a very modern design with modern coatings.
I just purchased a used one fron one of the RFF members and also have a new 50 asph summilux. The summilux sets a new standard but the Nokton 50 is very close even at 1.5. I personally don't think there's enough difference in performance and quality to justify any major difference in price much less $2,500.
You can purchase the 50 Nokton with a LTM adapter for about $400 new and have a lens that will deliver top quality and never need to replace it. I found my Nokton with a CV adapter in near new condition for $250.
Cosina makes some superb glass and so does Zeiss. I now use a mix of CV, Zeiss and Leitz. I feel I have the right mix for the work I do and have the quality that I want. I have no experience with Konica but suspect form reports and previous glass they've made it too would be excellent. Just because the price is lower than leica does not mean the quality is less.