Sarky comments on grain containing stone will show what you can expect to pay (4,5)
I believe the answer is:
list price
'show what you can expect to pay' is the definition.
I can't tell whether this defines the answer.
'sarky comments on grain containing stone' is the wordplay.
'sarky comments' becomes 'lip' (lip can mean sarcastic comments).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'grain' becomes 'rice' (rice is a kind of grain).
'containing' indicates putting letters inside.
'stone' becomes 'st' (abbreviation).
'lip'+'rice'='liprice'
'liprice' going around 'st' is 'LIST-PRICE'.
'will' is the link.
Can you help me to learn more?
(Other definitions for list price that I've seen before include "What manufacturer says is the cost of an item" , "RRP" .)