Crypto Currency is an uprising technology for payment. It is still in its infancy and by some regarded as a ponzi scheme. However, I read the paper on Bitcoin and it makes a lot of sense. In fact, I believe it could potentially be better than the "real" money we currently use because of its mathematical properties.
So, even though it is not "real" money, I've decided to accept it as a payment option in exchange for services, at least for a while. As a promotion, I will accept a 20% discount if using Bitcoin.
Other Crypto Currency could also be accepted, but I would need to check its validity first.
You can view the real value of, for example, Bitcoin here.
So, that means one can exchange it for real money. However, transaction costs are a lot lower and it is much more convenient over great distances.
20% off means 80% of the normal price at an agreed time. This could be time of invoice or potentially earlier to provide a fair game.