It’s a hard equivalency to make because weed gets cheaper in larger quantities. Wine does too but not on the consumer side (unless for some reason you buy cases of the same bottle all at once)

I know how much wine costs. I got bottle of wine in a restaurant for $35, at grocery for $4, in Spain at grocery for 1 Euro and free with 10 Euro meal in Barcelona. I know what one bottle of wine makes to my body. I don't smoke weed and I don't know if 1/8th of cannabis is something I could use in one evening, so it would be equivalent of bottle of wine.