Will start with an apology:- I have been a bit late posting, as they may have been at this price for a long while, sorry!
Do you purchase soya drink/milk? I have have for a long while. I have been a vegan for 8+ years, and have used it since then, in Tea and coffee, on cereal, and for cooking in general. Prices of the cheapest version have remained consistent, though prices in the different varieties/brands, varies quite markedly. I buy the basic, unsweetened, non chilled, variety. That un-opened will last for least 6 months+. When I first started buying it it was 49p a litre. I used Aldi, Lidl & Asda, changing when I noticed the prices going up or down. In those 8+ yrs, unlike cow juice, prices have remained remarkably consistent, from that starting point, until very recently, it had only gone up to 55 pence! which considering the rate in inflation is not too bad; a couple of weeks ago I was shopping in Tesco, and couldn't believe to see their Grower's Harvest, (farm grown) Unsweetened Soya Drink, Is 50p per litre. Only bought a Litre, as I thought this is too good to be true! It wasn't. As a bonus if you give it a good shake it blends in seemingly, in hot drinks. I have since bought all my Soya from Tesco. As Tesco is my closest Supermarket, within easy walking distance, I am delighted. While there, I have noticed they are reasonably priced for much of the stuff I buy!
Disclaimer:- Other super markets are and suppliers of soya are available. AND I have no connection to Tesco or received payment for this post! Ed