Its probably purple dyed fake bud from a legal high shop
Minimum ive ever heard of here for basic green bagweed is 70 quid an ounce which is 140 dollars an ounce and this is for a bulk buy many people pay a lot more than that per ounce.
I have heard of people even buying rabbit droppings and thinking its a good smoke once they've had a couple of beers.
Some food colouring,flavouring essence and some fake bud is probably what he got.
All that said and done though some growers have huge setups especially some rich dudes and they may well have mates rates so it is still possible.
I know a guy who grows many plants outdoors because he likes to grow but he doesn't really smoke much more than an eight a week and he has jars of the shit from over 2 years ago because he wont sell it and just doesn't use it up quick enough.
Ive known him for years and he once sold me an ounce for a tenner,not really a sale just a token gift thank you payment