My husband built us one with kind of an adobe house / southwestern cave dwelling look, to match our southwestern decor. One of our cats got quite a bit of use out of it, and still climbs it occasionally. The older cat never took an interest.
If you’re trying to get your cat to “adopt” a used tree, try Feliway spray. Not sure exactly what it tells the cats, but it’s sort of this-belongs-to-me vibe.
Since our cats are notoriously disdainful of anything we actually spent money on, an expensive cat tree isn’t looking too likely for us. I might have to look into a faux door frame, however, since my cat, Scratchy McScratchalot, really likes to do up our door jambs.
Try craig’s list the link is to the Seattle site, but it has links to many other cities. They often have them in the “free” section.
You could grow one from seed, but it will be several years before it starts producing any used cats.
Just to clarify, are you interested in having cat furniture where they can play and hang out, or are you looking for a way to keep them from scratching where they should not? If you just want to solve the scratching problem, those cardboard scratch pads work very wel for most cats, especially larger ones.
My own cats go crazy for the ‘Whisker City Play Cavern Scratcher’ from Pet Smart, and it has definitely saved my door frames and furniture. 
They have a cat tree too, and it was in my home at least three months before any of them would go near it, but now they like it.
Where were you with this little tidbit, when the blacklight thread was groing on in the last month? This would have fit right in with the other posts.
My cats are all over anything that smells like another cat! For new stuff, we’ve found a bit of catnip spray works for three of our cats. The two that don’t care about catnip end up getting involved because they want to see what the other three are up to!
Also, when we bring in something new, we hang some dangly toys from it go get their attention. They don’t have to be anything fancy. Thread a string through an old tennis ball using a carpet needle and hang it up. Heck, just crumple up a ball of paper on the end of a string!
We have a multi-level stratching structure with carpet, sisal, a play tube, and two platforms. There’s almost always at least one cat sleeping or playing on it. Interestingly, one of the platforms is just a flat carpet-covered board. They almost never sleep on it. The other has sides about 2-1/2 inches high, so it’s like a little box or kitty bed. That one is used all the time. They play in and on the tube, but rarely sleep in it.