'on offer' offer is a necessary step in a sale
'bargain' one side of an agreement, or both
'for only' yes, this is the price they want, big deal
is a 'low low price' a double negative?
same goes for this year's spout 'double-discount', which means the discounted price has been halved and done twice.
Answers:
"One time offer!" Yes that's right, after I have sold it I will not be selling it again
"comes with free......." Can I just have the free thing?
"Buy one, get one free!" I only want one, just halve the price!
"for the amazing price of only 9.99!" Pulling a wildebeest out of your left nostril is amazing, a tenner for a cheese grater is not.
"BANG! and the dirt is gone!" Am I the only person who spent hours trying to make a bottle of Cillit Bang explode?
"Would you like an extended warranty?" No thanks, just give me one that will break within twelve months.