For your budget, you are looking at used for sure for all your equipment listed.
I would look at Kubota used as there are likely many more to choose from and finding one in good shape might be easier than other brands. For 5 acres, a B model in 23XX to 26XX HP would serve you well. For 5 acres, you don't need more than 26 HP model of whatever brand you find. Craigslist might be the best place to find an used bush hog and even a tractor but beware of super deals as they are likely just scammers. Never buy a tractor unseen, or shipped to you after a paypal or other supposedly safe transaction. Scammers know how to put up fake PayPal accounts and otherwise. If it sounds too good to be true, IT IS.
Tractorhouse.com will give you some idea of what folks are ASKING but not necessarily what they are selling for. Search around your area by using the tractorhouse search by zipcode and within driving distance to see what is locally available.