Western NC. Better weather, lots of trail areas. Go where the retirees aren't for cheapest housing. Go where the retirees are for service job opportunities. If you want to retire, go to Asheville.
Plenty of good places to train for mountinous races in cheap areas. I would look at North Georgia, Eastern Tennessee, or Western NC. Specifically places like Chattanooga or Blue Ridge. Surely the only factor in where you live cannot be trail running though or else you would make it work in Flagstaff or Boulder.
The following sortable table comprises the 200 most topographically prominent mountain peaks of the United States of America. The summit of a mountain or hill may be measured in three principal ways: The topographic elevation...
West Virginia is cheap, but not too runner friendly. You would need to stay off roads and stick to public lands and away from the squatters with guns and meth who think "public" means they own it because they paid taxes once.
In Colorado, Alamosa (home of perennial DII national champs Adams State), Monte Vista, Westcliffe, Del Norte, and Saguache are all relatively cheap and adjacent to trails and high elevation. Canon City is affordable and has a highly underrated network of trails if you don't mind living next to SuperMax prisons. You'll have celebrity neighbors! Wyoming is cheap but I hope you don't mind the wind! Northern New Mexico is great, as other posters have said. If you truly want dirt cheap, the Pinhoti trail in eastern Alabama hosts a 100-mile race with comparable elevation gain to Leadville. Awfully warm in summer, but you can get a decent house in places next to that trail for under $100k.
Answer is Wyoming. No state income tax and cheap (excluding Jackson area). Wyoming is like the West Virginia of the Rockies...coal, Republicans, cheap living, and plenty of mountains in backcountry.
Wyoming is also the second highest state next to Colorado...so you get altitude training you wouldn't get in east coast.
If you want specific towns...Lander, Sheridan, Laramie, Pinedale, etc...
And..some of the world's best Ultra runners come here to race low key.
Pennsylvania. Or maybe Switzerland. But definitely not Ohio. Not a state, but Ithaca is nice in the fall. And in the spring I like to visit Santa Monica. There's a really cool little outdoor shopping area - I think it's on Third Street (if memory serves...I haven't been there in years!). I like to walk along there and then go to the pier. People there walk so slow! It's hard to get used to for an East Coaster. Like you just get stuck behind a whole family that's all walking like they have nowhere to be and there just isn't room on the sidewalk to get around them. People from that area drive like they're in the Indy 500 and walk like geriatric patients! It can be infuriating, but I try to calm down and not worry about it because otherwise I really like it there. Maybe some day I'll buy a little place there near the water. Not a big place. Not my primary residence or anything. Just a place to go in the spring when I want to walk along 3rd Street and then the pier. I'll always come back to the East Coast, though, where people know how to walk more than 3 mph and don't dawdle along like they have nowhere to be.
I laughed and laughed at the part about SoCal-ers driving fast and walking slow! I learned how to drive on the wide suburban boulevards, expressways, "parkways," and freeways of SoCal, and when the traffic relents, people put the pedal to the metal and drive--I'm talking 90 at least in the fast lane or get out of the way! If you're not moving, you will have someone riding your tail in no time flat! When I moved away, it was so bizarre and frustrating to find myself behind someone going 70 in the fast lane, just camping out, just cruising along, just taking their sweet time. But when I zoom out, when I think it over, when I analyze just WHY the SoCalers drive so fast when they get the chance, I'm sure part of it has to do with being stuck in traffic so often that when they finally do get the chance to move they want to take full advantage.
Driving in SoCal definitely has a more aggressive feel to it. It's such a pity how driving makes humans so angry. Speaking of SoCal, Disney did a great short film on the topic--in cartoon form--showing how driving caused an otherwise peaceful guy (I believe it was portrayed by Goofy or one of the other anthropomorphic "dog" characters) to become a road rager. And this had to be from the 1950's, when traffic was much lighter. My theory is that driving is such a mentally and physically stressful activity for the average human because it is actually extremely dangerous and our brains, even those with relatively low cognitive abilities, are smart enough to send the "danger" signal to our bodies. We react to the stressful environment with anger, aggression, etc.
I have never understood why ultra runners don't live in L.A. The cost is almost comparable to Boulder and you can have an actual social life. You're close to the mountains, it's better for dating, you can cycle and surf and do all kinds of things in the off season or when you're injured. The weather can't even be compared....Boulder blows in the winter unless you ski.
Not a skiier, but am a trail runner in boulder. The best part about the snow is that that when the steep, rocky trails get packed down just right, it removes a lot of their technicality and you can absolutely bomb down them. Local downhill test piece Green Mountain has a fastest "dry" descent of around 14:30, but Kyle Richardson ran down it in 12:40 a couple winters ago.
Tl;dr, winter trail running can be fun if you let it.
