As both the 2012 BMW 1 Series M Coupe and the 2012 BMW 6 Series Convertible have made their debut at the 2011 Detroit Motor Show today, pricing for the latest Bavarian models going on sale across US this Spring, was also announced.
The 2012 BMW 1 Series M Coupe price will start at 47,010 USD while the 2012 BMW 6 Series Convertible price start at 91,395 USD, both including the 875 USD destination and handling fee. 
The 2012 BMW 1 Series M Coupe comes with a 3.0-litre inline-six twin-turbo engine under its bonnet which is able to spit out 335 HP and 450 Nm of torque, and also thanks to which the car will require 4.7 seconds when accelerating from 60 mph from a stand still.
As for the 2012 BMW 6 Series Convertible, power is extracted from a 4.4-litre V8 that develops 400 horses and 450 lb-ft of torque, which get sent to the rear via an 8-speed automatic gearbox.
BMW press release :
BMW Announces Pricing for Detroit Auto Show World Premieres
Woodcliff Lake, NJ – January 10, 2011, 12:00pm Eastern Time… BMW
announces the base prices for several new models which debuted today at
the 2011 North American International Auto Show in Detroit. The
hotly-anticipated 2011 BMW 1 Series M Coupe will go on sale with a base
MSRP of $47,010. The stunning, all-new 2012 BMW 650i Convertible will
start at $91,375. Finally, the updated and better-equipped 2012 BMW 1
Series models will be priced as-follows: 128i Coupe, $31,825, 135i
Coupe, $39,925, 128i Convertible, $37,475, 135i Convertible, $44,675.
All prices include $875 Destination & Handling fee.
The all-new BMW 1 Series M Coupe, at $47,010, is a car built by BMW’s
most enthusiastic engineers for BMW’s most enthusiastic drivers, and
signals the youthful, energetic future of BMW M. Essentially a BMW M3
chassis with Competition Package packed into a modified 1 Series body,
the 1 Series M Coupe is one of the fastest, most remarkable M vehicles
ever built. It features one of the most powerful inline-6 engines BMW
has ever built, massive brakes, and a very wide footprint for maximum
agility and stability in the spirit of the original BMW M3, which was a
race-ready homologation special. The 1 Series M Coupe will be available
in limited quantity as a 2011 model.
BMW’s magnificent new 650i Convertible ($91,375) features a lower, wider
canvas on which the designers have crafted an elegant shape of pure
dynamic presence. Going on sale as a 2012 model, the 650i Convertible
features BMW’s 4.4-liter, "reverse flow" V-8 engine with 400 horsepower
and 450 lb-ft of torque. Two transmissions are available including the
standard 6-speed manual and BMW’s brilliant optional 8-speed automatic,
both suited perfectly to the sport-luxury mission of the 6 Series. As
with the previous 6 Series Convertible, the new 650i Convertible
features a super insulated folding soft top which can retract in a mere
19 seconds at vehicle speeds up to 25 miles per hour. The interior of
the new 650i Convertible features a fresh, ergonomic design with more
passenger space, improved ergonomics, and superb materials choices,
including optional full-leather trim with contrasting stitching.
Last, but not least, the popular BMW 1 Series Coupe and Convertible
models have received substantial enhancements for an early start to the
2012 model year. The 128i model has received BMW’s innovative Air
Curtain system, which smoothes airflow over the front wheels to reduce
wind resistance. All 1 Series models receive updated headlight and tail
light assemblies, featuring a new "eyebrow" design up front and new tail
lights at rear. Xenon Adaptive headlights – standard on 135i models,
optional on 128i models – add LED backlighting for the new eyebrow and
LED light tubes in the tail lights. All 1 Series models now feature
standard iPod/USB integration. Convertible models now feature standard
through-loading system for improved storage capacity, while 135i models
gain standard power seats with adjustable lumbar support. Convertible
models receive larger light-alloy wheels, now 17" diameter on 128i
Convertible and 18" diameter on the 135i Convertible.
The 2011 BMW 1 Series M Coupe, as well as the 2012 650i Convertible, and
1 Series Coupe and Convertible arrive at authorized BMW centers this
Spring.

Source: BMW