I dropped off my tank at CCFE tonight. I was quoted $12 for a refill. They just pick up the tanks in McKinney and haul them to Dennison for refill. Thus, the refill is not instant and will require parting with the tank for a few days. Since this is a new (empty) tank and I have no kegs filled yet, I don't see this as an immediate problem. I'm realizing now, though, that I didn't even get a receipt or pick-up ticket (didn't pay anything) for my tank, so that is a little odd.
-- Update 6-17-10 --
Got my tank back today. $12.99 after tax for a 5lb refill. It took 6 calendar days to get the tank back. The guy who filled the tank called to tell me it was full and then gave me a price of $20-something (the price included a hydro test). When I mentioned my tank was new, he checked his notes on the tank, agreed it didn't need hydro, and corrected the price to a CO2 fill-only price. He said they would not have performed hydro on it due to the 2008 manufacture date. I'd rate the overall experience "meh". As long as the phantom hydro charge was an honest mistake and not a mode of business for them, and you can live without your tank for several days, i suppose it is a decent option for tank refills in McKinney area. I think I'll look for an on-the-spot refill place for my next refill, though.