When you decide to buy a van there are a lot of things that you'll have to consider. The main one, of course, is what you'll be using that van for. Vans come in different sizes and styles, and a bigger van isn't always a better van if you're just getting it for a small family. If you're commuting to work every day in it and picking up a lot of people along the way, though, you'll want to buy a larger one. There are all kinds of uses for vans, so making sure you get the right one is very important and will generally revolve around what you'll be doing with that van and who else might be driving it. Not everyone will need a big van, and if you'll be driving it all the time and it won't be full of materials, equipment, and people, you'll really be wasting a lot of fuel (and therefore money) by buying a big van.
You also have to consider the price. The bigger the van the more it's going to cost you, on average. Along with that, there is the issue of whether to buy a new one or whether a used one will do you just fine. Again, most of those things are going to come down to how much you use the van and what you're using it for. If you're using it for ferrying a lot of people around you'll probably want it to be a little nicer than if you're only using it for carrying equipment or materials. Some people buy a van and they use it for their business. If you work alone you'll likely be looking for a van with no seats in the back so you can put boxes, shelves, and other things in there. If you need to carry people around, though, you'll need those seats. You want them to be fairly nice, too, so that people aren't concerned about the cleanliness when they ride in your vehicle. For carrying people, you'll want to look for a newer van.
You also have to pay attention to whether a van fits within your budget. Don't try to buy something that's so far out of your price range that you won't be able to comfortably make the payments. If the business you're buying the van for doesn't do as well as you had hoped, you might end up ruining your credit because you can't pay for the van, so try to avoid getting in over your head. You can find many nice vans for sale that have been previously owned if you're willing to look around and negotiate.