Villas can be super affordable when you're travelling with large groups. I'm the CTO of a startup that provides these sort of vacations. It's pretty common that the per person rate works out to much less than a hotel would be and you get the added bonus of an entire house!
Here are a couple of examples:
Sleeps 24 - $4,501/week - http://demeure.com/properties/villa-turquesa--2
Sleeps 13 - $4,569/week - http://demeure.com/properties/casa-fermentini