This is the recipe from the store bought packet. The packets are a bonus here as they are so inexpensive, and the Lobo brand, no preservatives, no MSG, and no colorings. You may have seen these in the store and may not understand what these are, instructions on how to prepare are in English on the back. Only a few people I have ever met make curry pastes from scratch.
Beef would cost about 50 Baht for 250 grams, chicken breasts would cost about 15 Baht, low cost anyway you look at this. For 4 servings using beef, this is about 37 cents per serving.