If you work in HSV, but live in TN, you will have to pay AL non-resident income taxes (AL Form 40NR). They're fairly low, though. TN does have a state income tax (the Hall Tax), but it only affects certain interest earning sources of income (dividends and the like). Less than 1% of Tennesseans pay TN income tax. sales taxes are fairly close in each state, with AL being slightly lower. TN does have a $0.10 per box tax on ammo, which goes to TWRA (TN Wildlife Resource Agency) to support conservation programs in the state.
A lot of people live in TN while working in HSV. Fayetteville, where I live, is only about 30 minutes or so away. Fayetteville is a lot quieter and a good bit safer than HSV. There are fewer dining and shopping options, though. But, the short drive to Huntsville does make it fairly convenient for dinner and a movie.
There are a number of decent places to live in Fayetteville, especially if you're looking to make the most of your money. If you're just looking for land upon which you can build, you can get 10 acres for as little as $60k. If you're looking for an already built home, with enough land to have a small farm, build a personal range, or just have room to ride ATV's, that's doable for quite a bit less than a lot of other places, too. In fact, there's a nice 18 acre parcel on Old Quick Road with a 3,000 sq ft, 3 BR / 3 Ba house with a couple of outbuildings currently on the market for about $350k. (Old Quick Road is right along the TN/AL line, so the commute to HSV would likely be about 20-25 minutes.) If you decide to look at properties up here, let me know. One of my clients is a real estate agent and I can pass along her name to you.
The gun laws are nice in both states. We both have shall issue permit programs and both have reciprocity with the other. In AL, the program is administered by the county sheriff and there is no training requirement. In TN, the program is administered by the State, there is an 8-hour class requirement (unless you are active duty military), and the permit is a little more expensive than AL. TN's permit, though, is valid for 8 years now and is accepted in something like 34 states. Both states are kosher with NFA guns, if you're into MG's, SBR's, cans, etc. There are a couple of good gun shops in the HSV area (Larry's on Memorial Parkway and Larry's West in Madison, in particular). Larry's son, Rob, is in the process of opening a shop here in Fayetteville sometime in the next few weeks, hopefully.
If you have kids, the schools in Lincoln County, TN are pretty decent for a rural school district. My oldest daughter is currently attending kindergarten here.
If you have any questions about the TN side of the line, feel free to shoot me an IM.