This is a thing I've been wondering about for a while now. Energy and labor are the biggest factors that drive supply chain costs in just about every industry. The more you spend on something, the more energy and labor likely went into creating it. Energy production obviously emits carbon. Some methods more than others, but with how immensely complex the supply chains are for most products (a global market with materials and parts and labor sourced from thousands of places all over the globe) I suspect it usually just averages out for the most part. Similarly, labor is done by people, and people all have their own carbon footprint. Again, some more than others, but with a global supply chain it sort of averages out.

So if you're spending significantly more money overall on something in order to reduce your own carbon emissions, there's a pretty reasonable chance (barring any detailed analysis to prove otherwise) that the cascading effects of that spending are actually resulting in more carbon emissions in total than if you'd simply gone with the cheaper solution.

Obviously this can't be universally true. It's a bit of a hand wavy argument, and the reductio ad absurdum conclusion would be that reducing global carbon emissions is impossible (which obviously isn't true). But I still think its something worth considering before making individual purchasing decisions based on perceived "greenness" to the demerit of price.

(I'll also note that if hypothetically a carbon tax or carbon credits were instituted globally then this price-based way of estimating carbon emissions would suddenly become not just a rough approximation, but a highly accurate measurement.)