That's expensive, 26 pounds ($35) for 3 gallons.
I found a thread about the beer, it sounds like it is just a regular ale with the sourness due to the addition of acidic fruit. Not a real kriek, but may be along the lines of Lindemans which is a lot sweeter than a traditional Kriek, and seems to be preferred by Women.
https://www.thehomebrewforum.co.uk/threads/brewferm-kriek-review.18201/
A traditional Kriek with complex sour flavors will take about 2 years. Looks like this one is ready in about a month.
If you want to go the traditional way, it can be pretty simple (or as complicated as you want to make it). A simple Kriek can be brewed:
- Extract wort to 1.050, minimal hops, and a max IBU of 10.
- Add a Belgium Lambic/Sour yeast mix
- Use a well sealed fermenter (not a bucket), and keep headspace as small as practical
- Put fermenter out of the way for 18 months. Ignore anything that develops on the surface (it is supposed to).
- After 18 months, add sour cherry juice, or move onto sour cherries (break the skins, but do not remove the stones). Leave for at least 3 months.
- Bottle as a normal beer. It may be slow to carbonate. You can speed up carbonation by adding fresh yeast at bottling.
Another option to sour the beer would be to go the Berliner route, and sour the wort for a week before adding yeast. This provides a less complex sourness, but can be more refreshing. For this you would need to use Lactobacillus (buy from yeast suppliers, use probiotic tablets, use yogurt sour mix, or other method) and maintain wort at 100 F (40 C) for about a week to get the wort sour, and then go through the brew process.
