I've seen lot's of dirt cheap six sigement trips on the UX website - but they almost always involve an eight hour overnight transfer in PMI - not so much fun.
Seperate question, In the past I've done some very cheap same day return bookings their Website (e.g. €121 return to Madrid on the same day).
Somewhere on the website it states "Trip must incude a Saturday Night", but the system lets you make the booking anyway. I've always ignored this and I've never had a problem with taking the flights - do you think it's risky?