Do you use a model with pigment inks or dye inks? I currently use a pigment based hp inkjet. I thought about switching to ecotank but the pigment refills are comparable to hp pigment cost. I assume the ecotank would get a higher page count from the same cost of ink? The pigment based ecotank models I shopped around were quite a bit more expensive than the entry level dye based models.
The markets where I buy are confident enough in their product that they cut the one you want to taste before you buy. I've never found a more reliable method than that.