Well if it has to be "sent away" there's going to be a fair shipping fee, or their fuel cost if they take a van load (there & back to deliver & to collect)
1st fill of my 3ltr 300bar 10 mile drive £10, so I never went back there.
Next place 5 mile drive £3 but a max of 250bar, sadly now closed.
Now got 12ltr I do a 20 mile drive for 300bar £5 while I wait.