After many years of all inclusive we went away last summer and ended up having a few drinks out. It surprised me how cheap it is now in many typical summer holiday destinations (Spain and Greece!). €1.50-2 for a beer, even better now the exchange rate has improved.
So this summer we went self catered for the first time. Beers and soft drinks the fridge, quiet pool area, few cereals etc… Then ate out every night. Spent less than we would on an all inclusive holiday.
Anyway to answer your question… Try Easyjet holidays, Lowcostholidays, travel supermarket (think you end up having to call travel agents who advertise). Do lots of research but take some trip advisor reviews with a pinch of salt!