PS are doing it now.
http://www.pokerstars.co.uk/special-...-price-sunday/
But i have seen it on other sites as well.
I dont see any real benefit in these for the players. They can offer the same guarantee because they can break the original guarantee with a cheaper tourney. It would be really half price if instead of 200+15 you could play them for 200+7.5. The way it is done now seems to be pointless to me.
Or am i missing something?

It's pointless. It's marketing.

Real half price would either mean half rake or that PS is paying the other half of your buy in.

THIS

+1 i like the 'pay half your buyin' option best