You can find a lot of older TTs under 20' for under $3000. Sure they're beat up, but it would be a cheap investment to try it out.
I actually did that - bought an 18ft for $1500 and put a new water heater & tank in it ($600). Kept it 3 years using it about 12-15 nights per year as I figured out my camping/RVing style. I could have rented something, but the money would have still been gone at the end of the day. All the supplies I bought where transferred straight to the clipper when I bought it. It ended up costing me about $60 per night camping over the 3 years. And I was able to fiddle around with it learning my way around RV systems without worrying that I would ruin something.