One of the cheapest, simplest and most effective treatments for psoriasis is exposure to sunlight. Spending 10 minutes out in the sun and gradually working your way up to 30 minutes of exposure can lead to improvement of psoriasis.
When using this form of treatment, be sure to put sunscreen on all parts of your body that aren't affected by psoriasis. And don't overdo it; you don't want to get a sunburn or cause your skin damage. You'll also want to discontinue use of topical treatments that might increase your sensitivity to the sun. Although it may take some time to yield improvement, catching some rays in a cautious way can lead to relief from psoriasis.