Western tack is pretty simple. You need a good saddle blanket (pad), a decent saddle and bridle. If the horse will work with it, I prefer a hackamore because it is less invasive. BUT, you have to be careful not to pull too hard on the reins as you can hurt the horse. For horses that don't respond well to those, use a snaffle bit. One person who boarded his horse with me for a while had a chain bit that was given to him. He couldn't understand the strange behavior of his horse untill I pointed out that his bit would seem like a mouthful of rocks to the horse.
Unless you intend to ride very little, avoid endurance saddles and get a traditional western style. The endurance type is very light and comfortable, which is good for the endurance of the horse and rider, but bad for the endurance of the saddle. I know a fellow who has to use them because he has a bad arm and can't pickup a western saddle. He wears one completely out every couple of years.