Sorry for the late reply, but (as oknish knows) I've been playing with sharks and dragons the last 5 days!
I contacted 6 or 7 online dealers for my 20" Monoblock E's. K1 had the best deal by far - thanks to Brabus164 for telling me about them. I'm in the South, so installation options by K1 are unknown to me. Brabus-usa recently removed their GL price list from their website but list for the 20" E's and S's was ~$1195. If memory serves, the 22's were ~$1500. I'd rather not post the discount in public so PM me for details.
K1 was very easy to deal with. I received the well packaged wheels via UPS about 10 days from ordering. They were shipped from Brabus' Miami distribution center. Shipping was $150 - less than anyone else I contacted.
The recently removed Brabus price list indicated 2 tire fitments for the 20" wheels: 295/45 and 305/40. Emails from Brabus stated the 305's were used exclusively, but the 295's were on their list at one time. I'm going with the 295/45 tires. Tirerack had a much better price than I could get locally - they had Pirelli 295/45 for $213/ea, which is what I will use - drop shipped to my local installer.
Emails from K1 as well as Brabus indicate the OEM TPM's are fully compatable with the Brabus wheels. Installation for me: removing the TPM's from the 18" stock wheels, installing the TPM's in the Mono E's, and mounting and balancing the Pirelli's is a ridiculously low $65 for all!!! That's from a Tirerack recommended installer that has only good reviews (gotta' love the south.

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I will be all in with tires, wheels and installation for just under $5k - which I think is a great deal for the Brabus/Pirelli combo. BTW, K1 includes bolts, Brabus logo center caps, and spacers in the price.
ALL the Brabus GL wheel fitments start with a 60mm offset and spacers are included to correct to final ET.
Right now, my wheels are in the garage awaiting the GL. My SR notified my today that delivery has been pushed back a week to 5/10.

I hope I've answered all the questions - if not, just ask.