Cheaper Chips?

High maintenance? No I'm not. But it doesn't help that Red Rock Deli (my favourite chips) and Kettle (kinda hooked on now) are at sky-high prices when compared to others.
Red Rock Deli at Candy Empire: 100g - $3.90 / 200g - $6.90
Red Rock Deli at Cold Storage: 100g - $4.10 / 200g - Not seen so far
Kettle at Cold Storage: 142g - $4.40

I went grocery shopping ystday to stock up on my impending "war" with lessons and exams which will end most probably in August. So I kinda psycho-ed my parents to go Vivocity, since my mum had always wanted to see the Giant supermart there (and they like to shop at Giant), and there's Candy Empire there. At Candy Empire, the only had Lime & Black Pepper and Sea Salt left. So I bought the 200g Lime & BP. At Giant, there's only 1 miserable selection of Kettle Yoghurt & Spring Onion.
I went to Cold Storage just now to search for my Honey Soy Chicken and Sweet Chili & Sour Cream. Cold Storage has it, but only in 100g packets. There was only 3 packs of chicken left, and 1 was burst. So, I took 2 of each, and took a pack of Kettle Honey Dijon and Kettle Cheddar. Just 6 packs of chips cost me $25 bucks!
I need cheaper supplies of chips!!!

If anyone see anywhere selling Red Rock Deli and Kettle at cheaper prices, please kindly let me know. These are the fuel for my brain to work during exams...