From the official Pinarello site, blurb below about the difference between the two versions. As to cost, as for all Pinarello, expensive! You should find some prices online if you search.
"The Montello Crono frame, the sensational time trial bike of 2007 remains unchanged for 2008.
It will, however, be joined by a new augmented version, the MONTELLO FM1.
Made from ToraycaŽ 50HM1K carbon fiber, it’s lighter than the original MONTELLO yet performs at a slightly higher level.
Alejandro Valverde and the Caisse d’ Epargne Team debuted the FM1 in the 2007 Tour de France.
The remarkable ride quality and performance of the MONTELLO are only enhanced in the new FM1.
It’s available in 6 sizes and is supplied with 2 seat posts allowing you to adjust the seat angle for a traditional crono or triathlon position."
Material: Carbon 50HM1K TORAYCAŽ Monocoque
Fork: FP8 Carbon 50HM1K TORAYCAŽ - 1" 1/8 integral system
Rear Stay: Pinarello CRS System Carbon
Frame weight: 1150 grams (Size 51)
B.Bracket: MOST Croxover
Sizes: 45 49 51 53 55 57,5
Crono: Seat Angle 74,5°
Triathlon: Seat Angle 76,5°