You may need a vehicle to pick up paintings and other pieces from artists and to deliver them to customers (if you decide to offer such a service).
You might decide that a medium size van would be suitable for this purpose. The cost of a van will depend on the size, make, model and specification. You could look at used examples as well as new ones. The older the van the less it will cost to buy, but some old vehicles may not be economical to run and may project the wrong image for your business. An alternative to purchasing a new or nearly new vehicle outright would be to lease one.
Don't forget to tell your insurance company that the vehicle/s will be driven for business purposes, possibly by several different drivers.