Can someone please give me a quick idea of what is a 'reasonable' price/ml for liquid, just so that I know a bad price when I see one 
TIA

TIA
this chart is very useful and up to date. whoever did this did a GREAT job!
https://docs.google.com/spreadsheet/ccc?key=0ApUX4l_CDyRxdFU4OFVRZzlaREdJWUZEUk0yUmpFOHc#gid=0
this chart is very useful and up to date. whoever did this did a GREAT job!
https://docs.google.com/spreadsheet/ccc?key=0ApUX4l_CDyRxdFU4OFVRZzlaREdJWUZEUk0yUmpFOHc#gid=0