How does the cost of van rental compare to renting an economy car?

In general a van will cost you between 80 to 110$ per day depending upon capacity. An economy car (compact) costs far less. Right now Budget has an offer to rent a compact for 159$ per week for example.

Due to the increased comfort and storage available with a rental van, most rental locations will ask you to pay about 150% the cost of an economy car. Vans also take considerably more fuel than economy cars, so it's a good idea to factor that into your considerations. Very rarely you'll find a rental location that has zero price difference between a car and a van.