Watch KSL classifieds in SLC. I see some really good deals, mostly rural and away from the Wasatch Front. Craigslist is probably the best resource just know about common misspellings and how to phrase it. Searchtempest has been recommended and I second that. Just learn the ropes on it. Single page lists aren't half as reliable as the individual city listings. Just be sure to "search surrounding areas".
And be prepared to travel. I found my unicorn Northstar American Hero flatbed camper in Red Lodge Montana. I called a bunch, got familiar and developed trust with the seller and sent him a Venmo deposit sight unseen. Quite the GULP experience but it worked out. Especially as I didn't have any way to tie it down to my flatbed so I had him measure everything 15 times and I showed up with tools, straps and a plan.
Best of luck.