My dogs also love plush toys but have them ripped to pieces in mere minutes. We bought a tougher toy at a pet expo last summer and it managed to last quite a bit longer than most of them but it wasn't cheap. My dogs do like those plush animal ones without stuffing as well and they do last a little bit longer since they aren't trying to get the stuffing out. Everything we have ever tried has ended up in pieces within a couple days at the most. I too just buy the cheapest ones I can find, usually whatever is on sale at the store from the last holiday.
ETA: I looked it up and the tougher toy we got was a dragon made by Go Dog. I really was a good toy and if I saw one in a store close to me, I would buy another one or two.