I installed an Audiovox CCS-100 in my 4-cylinder 1988 Mazda truck back in 2002, and it has worked pretty well since. But that only cost me $100 (AutoZone), looks like more now, may not work in "modern" trucks.
I'd be interested as well, I have 1998 and 2004 Frontiers, both 4-cylinder and manual transmission, that do not have cruise.