Hm, I'll have to keep an eye open for some of those names on craigslist. I could manage to up my budget a little. It's really to keep solely at work...I work in a drive through emissions testing bay (look it up if your state/area doesn't have emissions requirements) which is literally a self-serve carwash bay turned into a small testing facility, & I have roughly 8-9 hours of free time the two days a week that I work at that shop. I'm outside (sans the roof over my head) 10 hours a day with nothing active to do, & a bike trainer sounds awesome compared to nothing.
As for running, I just like having obstacles to run/jump over, kind of like freerunning but without feeling like a fool for sucking at it
The obstacles that seem small & unentertaining on my bike are slightly more thrilling when running, so I like to change it up every now & again to regain appreciation for my local XC trails. That, & road running is killer on my knees...I don't know if doing it more would strengthen them, but they lock up & hurt badly after ~3mi on the road so I generally avoid it.