Half a litre of Silca Chain Stripper is 44 euro. Whole litre of white spirits is what, 2 euro?
I mentioned two products, the other one was UFO Clean which is £22.
The cost of the product is one factor but not the only one. First off, half a litre of either of the above will strip 25 factory chains of lube - so even from a price perspective, how much white spirit and meths (which btw is £5 per 500ml, so quadruples your price comparison) will that need?
The next factor is time, what do you want to do. Three baths of white spirit, followed by 2 of meths, then wax....or soak in UFO Clean, give it a couple of shakes occasionally, move chain into a foil tray and immerse/rinse with boiling water, then dry and you're done. In the latter case the chain will also have a coating that it's claimed (and I have anecdotaly found to be true) helps with the wax adhesion to the chain.
Then there's the question of what to do with it afterwards. Used White Spirit (unless you have a fancy recycling facility at home) will require taking to the tip for proper disposal. Used UFO/Silca should also be properly disposed of, but as the initial chemical is environmentally friendly you could arguably use the 'used' stuff which still has some cleaning power to do some cleaning of chainrings etc and rinse it off, which is still better than doing the above with a harsh degreaser.
You pay your money and take your choice, and I've done both. I get paid to prep chains and regularly go to the tip to dispose of chemicals, so if I thought White Spirit/Meths was better/cheaper/easier I'd still be using them but the time saving and the guaranteed result means I mostly use UFO Clean.
For the home waxer using drip wax, I find it very hard to recommend anything other than the Silca Bundle - for 8 quid more than the drip wax itself you get the wax plus the stripper (only enough to do 5-6 chains, but still....), and you never have to even worry about taking the chain off. More experienced people who do immersive would still benefit from having some drip wax lying around for those lazy times or after getting caught in rain when you need to do something but can't be bothered with a full strip and rewax.