I would contact a CPA. There is a lot that can change or a lot that you won't know unless you delve into the IRS. You can get in pretty deep if the IRS starts poking around and you haven't done things correctly. With that being said though, I would buy. I don't know very much, but I know there are situations if you are only using the vehicle part time for business about how much you can depreciate, mileage, etc. I've never liked leases, I want to own whatever I have.
I am not sure if we are talking about a $20,000 vending business or $200,000 business. If we are a talking about a larger business, I would definitely contact a CPA. They can keep you out of IRS trouble and give you sound business advice.