You can have a complete ph system for about 50 bucks. I go to my local walmart or petshop and buy water ph test strips. i get 100 tests for 5bucks. test the runoff water from ur pot. you can buy pH up and down at your local pet store, about 15 bucks each a bottle. I also buy a pH balancer (comes in a tablet, dissolves in water) can buy that for 10$ also. it keeps my soil around 6.8-7ph for a while so i dont have to keep adjusting every time i fertilize. so thats 5+30+10 so for about $45 bucks plus tax you can have a complete system that works amazing and lasts a long time for the money you pay.
all this can be found in your aquarium section of pet store. though if you do have the money i suggest buying an actual ph meter as it will give more accurate results and can last you years and years with out replacing it.