If you're only growing for personal use, you may not need that big of an area. In a 4 x 4' size area you could easily grow 4 big photos, or more smaller ones, and up to 16 or 20 autos. You might consider starting out with a smaller area, designed to it can be enlarged later. I have a small 2' x 2.5' area that is big enough to grow 4 autos at a time. I can routinely pull 6-8 oz. every grow. I use a 240 watt LED that gives excellent results. Since you're on a tight budget a smaller area would of course be a little cheaper to set up, mainly because of less lighting needed.
Click on the Automatic Seeds link at the top of the page, then Mossy's Medical Seeds. You will find a Purple AK there are a very reasonable price.