Here's my experiences filling up while going XC:
Boulder Gas on 28th St. Boulder, CO
-unknown source for B99
-available by the 6 gallon jug only: you take their jug, fill up your car, and give it back. very messy. unknown how/when/where those jugs are refilled.
-cost was $1/gallon more than petro diesel
Jay's Garage, nr 7th & Hawthorne, Portland, OR
-gets B99 biodiesel from SeQuential Biodiesel
-cost was 40 cents more than petro diesel
-high volume station (lots of bio customers), also do diesel repairs
Prairie Fire Biodiesel Co-op, Washington Ave, Madison, WI
-buys commercial B99 from changing/"unknown" sources in the midwest
-pump is inside garage bay, there are member price and non-member prices
-non-member price was 90 cents/gallon more than current price of petro diesel in Madison
Gas Up, Haymarket St, West Asheville, NC
-supplied by Blue Ridge Biofuels Co-op, which produces their own biodiesel, ~250K gallons annually
-B20 and B99, both cost-competitive with petro diesel
-3 outside pumps, bulletin board with lots of info about biodiesel + what you need to know about rubber hoses, their operation, etc.