The EI method is probably the least expensive. I don't know what you've read to make you think it is expensive but at the end of the day all you pay for is the tapwater you chnage every week and cheap substances like KN03, KH2PO4 and K2SO4 of which for example 250g of KN03 will last near enough a year on the average tank.
I premake solutions and yes you do add things everyday but compared to measuring, testing or buying premade ferts it is by far the cheapest and I make solutions up, then put each days solutions into small bottles, so that I can get up in the morning and chuck the contents of a small bottle in the tank then go to work. Takes probably 1 minute to detour to the study, open the cabinet, open the tank flap, shake then open the bottle, pour it in etc.
Andy