I understand your point of view, you are reluctant to spend large sums of money but will spend the smaller sums.
It is difficult to compare prices as the offers dont always contain the same elements, but often if you wait and buy a big pack, its more economical that buying lots of small packs for the same total.
Again just like in shops you have to watch for the marketing ploys with any sales or special offers.What you have to do is not buy to often as I have notice the more you buy or more often you buy the prices goes up.
If you buy and 5.00 pack a week there will always be 5.00 packs If you buy a 10.00 pack all others change to 10.00 and Up and so on. Wait time for price dropping down to normal is about 2 weeks to 30 days from my findings.
They see "watching your every move" you spending money so they want to try to make you spend more. Why do you think they make you allow cookies in order to play this game? "so they can track you"
I just wait it out "now if they'd leave small price packs in all the time I'd buy more often" so it's their loss. lol
You have to think outside the box on people like this, beat them at their own game.