Consider slightly used, rather than new?
If you are not pulling a fiver, you can usually get a 6-12 month old E-350 passenger van with 5.4 V-8 at about 20,000 miles for around $20,000, that's XLT trim and full set of seats, coming out of the rental fleets or a one-year lease. Original price was close to $30K.
No 4x4, however.
I never see deals like that on work truck versions of pickups, even coming off lease with 2-3X the mileage at two years. Those will also usually be V-6 or the smaller V-8, and very seldom are they 4x4. Expect 70-80% of price new, on fleet 1/2 tons, rather than the 2/3 typical for used passenger vans.