Have you guys noticed? Wizzair has announced All You Can Fly programme. Pay €500 and then just €10 per each flight within one year. Sounds like something I might be into :)) I only regret they don't operate a direct Prague-Madrid line - I fly this one like five times a year. Anyways, there's likely a catch or two.
https://wizzair.com/en-gb/information-and-services/memberships/all-you-can-fly