I have six tanks to fill, what with the grill, heater, smoker, and two deep fat friers. My last trip out, I went to Texas St Autocare, where they charged more than $4/gal. I filled one tank and did some shopping around.
The place that I used to fill my tanks on Poway Rd converted into a minimart; they weren't cheap but not too bad. I just paid $2.39/gal in Colorado, but that was to fill 500-gallon tanks (in the Delta area, JC Propane is by far the cheapest).
Here's numbers I found. There's lots of other places, but these were listed. This is as of 22 Apr 2010. Some prices were per tank or approximations, so these should be considered ballpark.
|$2.83||Ferrelgas, 858-271-4400, 8088 Miramar Rd.||5 gal min, no price break.|
|$3.60||Westair Gases 858-578-1999, 8025 Arjons Dr.||"Coming to about $19 + change after tax".|
|$3.69||U-Haul, 858-271-7753, 9650 Camino Ruiz.||At 10 gal, reduced by around $0.50.|
|$4.25||Mission Valley Shell, 619-295-9829, 5465 Mission Center Rd.||$21 minimum.|
|$4.80||Ultramar, 619-296-4913, 4616 Texas St.||Exchange only $23.99+tax|
|--||Amerigas, 858-578-6513, 9350 Miramar Rd.||No BBQ tanks.|