The upgrade path used to be pretty liberal, until last year you could skip two releases and still catch an upgrade. I think I've spent about $1800 total over 11 years: Macromedia MX Studio (2002) > CS3 Web Premium (2007) > CS6 (2012). That's a just over $13 a month. Not cheap when time comes to upgrade or lose eligibility, yes, but much cheaper than $50 per month in the long run. It really depends on the user's upgrade cycle.