There are a few ways to go about it, a treadmill that really will hold up or one that likley will not but has a long warranty, e.g. the manufactured assumes people don't really use them anyway.
The later may be the cheaper. Check out the Reebok's available from COSTCO. They have sales where these things are dirt cheap, like $600 DELIVERED, and some of the models have like a 20 year motor waranty. The are "cheap" and no frills.....I have one. I beleive they are made by ProForm, which has one of the worst reliability ratings (I also have a broken one of those laying around).
To cover the other stuff you can get a squartrade waranty, they also go on sale, and the price is low since the treadmill value is low.
Or you could pay a few thousand and have somthing that still basically sucks (I mean it's a treadmill....)