This information, (while it isn't necessarily for a kidney-related diet), has some very good ideas that may be helpful to you. I have to watch my sodium, due to allergic reactions, so I've actually used a few of these substitutions myself.
Choose:Sodium (milligrams) Instead of:Sodium Milligrams)
Lemon juice (1 tbsp.) 0 -------------- Soy sauce 1,320
Fresh cucumber (1 medium)14 --------Dill pickle 1,900
Salt-free bouillon (1 cube) 31---------Regular bouillon 960
Fresh peach 0 -----------------------Canned fruit (1/2 c.)10
Fresh green beans (1 cup) 5---------Canned green beans 925
Orange juice (1/2 cup) 1-------------Tomato juice 320
Fresh ground beef (3 oz.) 57--------Beef hot dog 425
Frosted Mini-Wheats (1 oz.) 0------Rice Krispies (1 oz.)290
Popcorn, plain, air- popped (3 c.0)-- Potato Chips(1 oz.) 133
Adapted from: Moser M and Becker B. Week by Week to a Strong Heart. Emmaus, Pa.: Rodale, 1992.