A place with great selection and very reasonalbe price is Super Food Mart in Temple Hills, its only a few miles from Alexandria and they got shit load of brands, including Mr. Nice Guy, Head Trip, Aloha, etc etc. Prices are around $10-$12 too not that crazy rip off. Go there and support them.
Super Food Mart
4705 Raleigh Rd
Temple Hills, MD 20748
301-899-0967