It sounds as though you're asking what food cost is for these items. That is a question only you can answer. My food cost isn't the same as yours.
You need to determine what your salads will contain, price the ingredients, build a representative model of the item, then weigh out each of the ingredients (much easier to weigh as you add instead of constructing and deconstructing later). So, if you pay $2 for a head of iceberg lettuce and the average head yields 16 ounces of usable product, then the cost for iceberg lettuce is 12.5c/ounce. If you use 4 ounces in the salad, then that's 50c in food cost. Note, I'm pulling numbers and pricing out of thin air, so don't even think they should be remotely accurate. Once you have the cost of each individual item, add it all up and that's your food cost for the salad. Add in gross profit margin and you have your final price.