On a tight budget, a stick and rag airplane is probably the least expensive way to go. Tube, stick and rag is probably the next least expensive way to go. All metal will probably be the most expensive route. A Pietenpol is one of the least expensive routes on a stick and rag airplane. There is a large base of builders on the Piet, so there is a large knowledge base out there. There are quite a few people currently building using a Corvair conversion for power. In the Birmingham area, you are fairly close to sea level, so you don't have to have as much power as you would in the Denver area for example. The piet is not as sexy as a Sonex, but it is a fun airplane, and can be built with much lower expense. There is a chat group here: http://www.matronics.com/Navigator?Pietenpol-List where you can get a lot of information. If you post on the chat group, please use some courtesy, and research the archives before you ask questions. Some of the questions you have, may have been asked a month ago, or even a year ago, and the answers will be there. The plans for the Piet are not expensive and can be found here: http://www.pressenter.com/~apietenp William Wynne, who many consider to be the leading expert on Corvair conversions, has a website here: http://www.flycorvair.com
The Pietenpol can be started on a small budget, and materials purchased as finances permit. Most of the builders start with the ribs, for cost and space reasons. It doesn't cost much to build ribs, and it doesn't take a lot of space. Tail feathers next, same reasons. The powerplant is probably the largest single purchase on any homebuilt. In case any of the links don't work, you can do a cut and paste, and that should do the job.
If the largest priority is to build an airplane that you will be able to fly, do some more research, decide what is realistic on your budget, and go from there. Speed costs more money. Most of the stick and rag airplanes don't set any speed records, but they still fly, and many fly quite well. Being in the air is what it is all about.