This is very difficult because of the terminology 'fail'. Most of the products out on the US market fail to identify themselves adequately. CG do some dedicated foam cannon products and Auto Finesse Avalanche is an example of what you would find in the UK (strangely, we are miles ahead here).
In practice, a snowfoam should probably be more closely related to an APC. Ideally you want some alkalinity since this provides the cleaning power but you want to make sure it does not contain sodium/potassium hydroxide - this starts to risk your LSP, not to mention chrome trims etc. Since alkalinity is cheap, so thus are the products - $20 for a gallon is about the right price point. I cannot help beyond these recommendations as I am in the European market and most of our products are not available in the US.