I'm not aware of any kind of devaluation in terms of real estate prices from kudzu. In the southeast, typically for small acreage (say under 20 acres) the market is for people who want to bulldoze everything and build a McMansion and giant metal shed/workshop/garage. Larger acreage is usually for commercial development or tractor-based farming unless it's good pasture or timber (and sometimes even then).
For all of the above I
should say "for land that has been advertised for sale." I can't say what happens in the informal market, but as a stranger you will be hard pressed to tap into that market anyway. But no, average people don't see kudzu on their property and then assume it's worth less.
That said, you can find some mighty nice
permie acreage in kudzu land, without or without the vines, for a reasonable price. Finding affordable land near employment is much, much harder, but I suppose that's the case anywhere.