Potassium tablets are ok and cheap but only come in 99mg. They can upset stomach so you end up taking them only with meals and personally I couldnt tolerate more than 3 per meal and even that sometimes upset my stomach.
Logging my food for a while I realized I needed to supplement a couple thousand extra a day so it wasnt very practical but the best I could do for a while.
Then when I added vitamin C to my regimen I discovered potassium ascorbate (4000mg ascorbate/700mg potassium per teaspoon) and its a great way to get vit C and potassium. I take 2 servings of that a day, sometimes more on workout days and then use ascorbic acid for the rest of my vit C needs (currently taking about 15-20 grams a day).