Not quite. The now discontinued 85/2 Sonnar used to sell for around 2600$ while the 90/2 cron sells for 4000$.
There is no equivalent for the ZM 15/2.8 Distagon (4600$) in the Leica line, but it is safe to assume it would cost no less than 7000$ if it existed based on the pricing of other lenses.
Of course the Japanese made ZM are only about 1/3 of the equivalent M glass approximately.
By the way, from what I've seen, the Sonnar seems to be on a higher optical level than the summicron, especially wide open.
a 90 non APO isnt 4k tho. APO corrections are some of the more expensive ones, as Im sure you know.
and how much is the Canon 85mm f1.8 again? lol. not saying it's in the same realm, but that is a lens most people consider to be reasonably priced. even the 85L isnt as much as these two f2 lenses at nearly 2 stops faster.
btw, Sonnar better than Summicron? at f1.5 compared to f2? maybe you mean Planar, because the Summicron and Planar both decimate the Sonnar as far as contrast at a given resolution goes at equivalent apertures.
as far as Planar vs Cron goes, well the Cron tends to test better at MTF50 but it's hard to know who wins this battle overall. Zeiss' MTF graphs are incomplete even compared to Leicas, and we cant directly compare them except at f2. If you've ever taken a look at the 50MP's graphs at f4 (they are actually out there if you look hard enough) that lens isnt any better than the ZM Planar but that doesnt mean you can assume the Planar goes to MP levels at f5.6. If it does then yes, that lens does in fact pull ahead of the Summicron.
but, if not, then the area under their mtfs probably equals out and then the cron is smaller and has less distortion.
the summilux ASPH is better than both though, and you pay for that. both in price and in its strange way of making itself look like a telephoto lens at larger apertures.
as far as I see it, the difference is purely in the price point between Leica and Zeiss. at the same price I dont think either would be able to make a lens that is strictly better than the other.