In the UK:
Sheffield Insulation

Rockwool: RW5 slabs - 100kg/m3 - 1000mm / 600mm
RWA45 slabs - 45kg/m3 - 1000mm / 600mm

+ various others, can get all varieties in within 2 days. V. friendly and helpfull. And.. V.Good prices.

Denver CO folks:

Eagle Rock Supply
2645 E 74th Ave
Denver, CO 80229-6619
(303) 289-4151

they can get all the 703, 705, and the faced 705 at a much better price than all the online suppliers are sell it at. only down side is they dont stock it so you have to purchase 12 panels at a time because thats how OC sells it. i still got 12 two inch panels for less than the best price i was seeing 6 of the same online.

Baltimore Maryland :

Supplies Unlimited

2201 Halethorpe Farms Rd
Baltimore, MD 21227-4598
410 247 9090

http://www.baltdoor.com/
(website is useless, call and ask for Supplies Unlimited)

Prices (2' x 4' panels) :

703 2" - 12 panel box - 88.00
703 fsk 2" - 6 panel box - 114.00
705 2" - 5 panel box - 62.20
705 fsk 2" - 6 panels - 70.20

Helpful and friendly!