You don't have to spend a ton of money to buy your cat a really cool cat tree. Amazon has a huge assortment of cat trees all for less than $100. I've posted a few of them here. Take a look and see what catches your cats fancy. Chances are he'll probably want all of them and I know how hard it is telling your cat no sometimes so be strong!
Go Pet Club 62″ Tall Greyish Black Cat Tree Furniture
62 High Grayish Black Cat Tree
Material: Compressed wood, post wrapped with carpet, cat tree faux fur
For small cats