Hi Scott!
I also want to thank you for your service!
I think most people have already touched on the niche marketing you'll have to fall into as a blacksmith. Most people take it from making horseshoes to hoof care. That works best if you settle in an area that is economically stable enough that people still keep their horses and care for them well. If the economy is poor, fewer people have luxury animals like horses--- or they try to cut corners and ferrier work is one of the first things they try to cut.
Some people do decorative stuff, or making historical reproductions like armor or swords for living history use and decoration-- but that would be rough trying to compete on ebay against outsourced big manufacturers, I know it's like that in costumes but it might be worth looking into.
A few years ago, I used to do civil war reenactments and there was a guy who had a travel forge and went around to all kinds of events. He made his living selling small items like forks, or nails as souvenirs to the public, or for the reenactors. It was fun for him because he could stretch himself creatively and make pretty much any tool or "cool thing" he wanted as long as it fit the time period and someone would eventually buy it.
If you think something like that could be for you, you need to take into account where you will buy property to make sure it's central to a vibrant living history area rich with SCA and other living history clubs that host a lot of events to minimize travel costs.
If you go this direction, you'll also need to lean towards animals that are more "easy care" that can handle you traveling all summer... there are plenty of strategies to schedule things around, especially if you live somewhere with a very mild winter you can safely schedule things during the "off season" in winter months like birthing season.
Also, a side note with a conspiratorial wink-- I can't see a strapping young blacksmith lasting a single summer reenacting season without meeting LOTS of the "right type" of eligible ladies. That environment is like speed dating for "old fashioned" singles.
To get an idea of how far your purchasing power will go, check Landsofamerica.com and see what comes up with your parameters. You will probably see lots of Missouri, Arkansas, Kentucky, Tennessee some Georgia and a little Texas.
Be sure to look into the politics and demographics of each area too to make sure you can live with it-- I recommend citydata.com, the forums there are set up by states and metro areas and the locals are happy to answer questions and give you a clear picture of what you can expect.
Congratulations! The planning is the absolute most fun and uplifting part of coming home!
Finally, here are some books I can recommend.
This is a book written by a UK author, but the information is priceless, I have a hard bound copy, but you can't beat a free e-book.
http://www.rivendellvillage.org/The_...ufficiency.pdf
Already suggested, and I confirm it's an incredible book:
http://www.amazon.com/The-Backyard-H...yard+homestead
Designed for making the most of a small space, and covering all the basics at a beginner level, you can't go wrong with this book weather you get a little parcel, or a large one.
I liked it so much, I also ordered:
http://www.amazon.com/Backyard-Homes...xgy_cc_b_img_b
...When it came out. It's expanded on the information in the animal chapters in the first book.
Storeys Guide books are also generally extremely good (we even have some writers from the series on this board).
I recommend subscribing to Mother Earth News as well-- the subscription is cheap, and you get a virtual subscription at no additional cost that you won't have to wait for while you're on deployment.