Buying a bus is a huge investment so to save money you may want to look at used ones. There is often still plenty of life left in used buses so don't think that they have all been used up. Some car rental companies and businesses replace their buses at regular intervals regardless of how much life is left in them. They may decide to upgrade to different models of buses as well.
Finding these types of used buses can definitely fit your budget as well as serve your needs. It is important to really inspect the used bus though to find out if it has any mechanical problems. You don't want to buy something that won't be reliable or last a long time. If you will have to put plenty of money into the used bus to keep it operational you should keep on looking.
Of course you may find a used bus that needs some repairs and it is still worth buying. For example you may come across one what needs a new engine in it. Even if this costs you $5,000 it is still going to offer you a very good operating bus that you will get plenty of use out of. As long as the price for the bus is reasonable this $5,000 upfront investment may be something you want to consider doing.
There are plenty of places where you can find used buses. You can talk to schools and rental car companies. Retailers that sale new buses will likely have plenty of used ones as well. This is because they could have been part of the trade in process when they were committing to buying a new bus.
You can also find used buses online from various dealers. You can narrow your search by your geographic location if you want to. Some dealers will work out a deal for you to have the used bus delivered as well. However, you are better off being able to go see it in person before you commit to buying it.
To get a good idea of how much a particular used bus is worth, use the resell books dealers have or that you can access online. You will need to have the year and the model of the bus in order to look it up. You can then add and subtract the value based on the features and the miles on it. This is good information to have readily available before you start negotiating the price of a used bus.