I am looking for a source of historical intraday data for futures and stocks, something like 1 min or 5 min bars. Preferably it would be some sort of a service that would provide me with the inital data sets and a daily updates (I do not need it to be updated in real time). So, here are the questions: (a) who are the reliable providers? I did google (obviously), but there are a lot of services with a wide range of prices and I want to hear what people use. (b) what purchasing model should I follow to keep it cost-effective? Should I purchase a full set or should I preferr to purchase a la carte per symbol/time period? If i do go with the partial purchase model, do these firms provide partial updates?