Grain free dry cat foods have several levels of quality:
Best: High protein (35%+) with all protein coming from meat sources. (Examples: Orijen, Wilderness, Instinct, Go Fit & Free, Wellness CORE original)
Mid: High protein (35%+) but includes some pea or potato protein. (Examples: Taste of the Wild, Earthborn, Fromm 4 Star, CORE Tky/Duck or Indoor, Merrick Purrfect Bistro)
Mid: Lower protein (<35%) all from meat sources (Examples: Evanger's Meat Lovers, Now!, Wild Calling, Acana, Blue Buffalo Freedom)
Lower: Lower protein (<35%) with pea or potato protein (Examples: Natural Balance LID, Halo Spot's Stew, Science Diet Grain Free, Science Diet Ideal Balance)
Price can vary wildly and there are foods in the lower category that are just as pricey as the best. IMO if you can't afford foods in the Best category, then the best bang for the buck are Taste of the Wild, Earthborn and Evanger's Meat Lovers.
I created 2 "Mid" categories because there is a distinction...the question is which is better...higher protein but some sourced from plants or a little lower protein but all sourced from meat but with a higher carb level. I lean towards the high protein with some from plants as being the better choice.