Hi everyone pretty new to this forum nice to meet you all

Ive been playing around with facebook ads recently. Facebook advertising coupons where initially free to my understanding.

Now there seems to be websites selling these coupons and even on ebay.

Has anyone ever purchased one? Is it reliable?

The coupons seem to be on sale for much lesser value than the advertising value they are worth which makes me a little suspicious. This would mean for example : paying £30 for £100 worth of advertising credit.

anyone have any views or previous experience with these?