I made a bet of 4 euros.
I created a new account, signed up for the newsletter and bought MFreeFXBundle with a referral code (-20%) + 10 credits = 4 eur. The upgrade to MCompleteBundle would be 724 € . So that didn't work, but maybe it saves someone else the trouble.
If one doesn't have a lot of plugins, using the -20% referral code for buying the MCompleteBundle would be the right move. If you already bought some, creating a new account would be necessary I guess.