Ive had both Hydro and mechanical. The nice hydros were just awesome and my mechs do get the job done but they are different bikes and different uses.
IT sounds like in your case with the combined shfters it might be more expensive depending on what group set you have, but I just picked up a left and right shifter for my fatbike ( I wanted rapidfires vs the ones that came on it) for under $40. These were more entry level Altus shifters but they are Shimano but I never had issues in the past. Better ones are still under $100.