Look on eBay. I don't have a treadmill as I don't think I could stand the boredom, so I can't really help with that. I have a rowing machine (eBay) and a crosstrainer (Argos). I don't know why they seem less boring, they just are. And I guess it gives me a slightly different workout from running. They get used about once a week once the kids are in bed and I'm trying ot fit in 3 runs. If I only manage 2 runs, sometimes I'll use the machines twice a week.
I would recommend a tv, DVD player and something that will get you moving (I'm working my way through Glee - lots of up tempo songs and teenage angst and it doesn't matter if I miss a line or two) with wireless headphones.