To be frank, the cheapest combined way of holidaying there is probably an 'off peak' package with Budget. As one can get a week in canaries generally during the 'winter' excluding school holiday period from under 300euro per head, its hard to beat this when you add up the cheapest flights and getting rental accomodation there yourself, when you also add in airport transfer stec at other end.
I rent a place in gran canaria from around 50euro per day which is typical costs there,and would use this option at Xmass when package prices are high, but other times it would be cheaper to go 'package'
R