Which Treatment for Body Hyperpigmentation (Freckles) is Most Cost-effective/long-lasting?

I'm aware that several treatments are suitable for dense freckles covering the body (arms, shoulders, etc.), but they can vary widely in terms of cost and duration of results. Which is the most cost-effective choice, assuming that I follow all post-treatment instructions to the letter and plan on redoing treatment when the freckles start to return? Background info- I only have freckles on sun-exposed areas where I frequently sunburned as a child. I tan in other areas, e.g. chest, thighs, etc.