Plenty are available for European games and cup games. Don't believe the hype that there are hge lists of people wanting season tickets. When my uncle died the club offered his season ticket firstly to my dad then asked if he knew anyone who wanted it. Not the actions of a club with these huge lists.
It does make me laugh whenever they interview fans outside Old Traffotd they always seem to find the non manc, whereas City always seem to have Mancs.
A mate of mine has been on the list for years and finally got his ticket at the beginning of last year. the fact remains that United play to full houses every hone game. Not many Euro matches this season though.