the by product ingredients and other problems in commercial cat foods? Ember will eat dry kibble or canned moist food.
Regarding cat trees, yes, they are quite expensive. Ember was such a climber and leaper from the start as a tiny kitten that I knew she would need something to satisfy her need for high places. When she was a year old, Big Lots had a couple tall cat trees on sale for $70. So I bought one. (That was before I retired, when I could afford it better.) It is solid and well balanced. I saw a couple cat trees recently at Big Lots that are not as tall marked $130. If the smaller ones cost that much at Big Lots, I am sure that they cost much more other places and the tall ones would be even more.
The shorter one that I have is from a previous cat. I tore off the shredded carpet covering on the tree's posts down to the bare wood, then sanded the wood smooth. Sometimes Ember naps on it. Other times she uses it as a stepping stone to the taller tree.
A few years ago I bought her two tunnels at Wal-Mart for around $5 each. A couple days ago at Wal-Mart I noticed that they no longer carry that kind and the ones they had were around $40!!
When not perched on the tall tree, Ember likes to go up to the space between the ceiling and upper cupboards to supervise my cooking and sometimes to freak out strangers, like the fire inspector for my apartment building when be shows up each year. (She doesn't like him.)