I have a medium sized (about 2m by 1m) temporary bench in my framing barn, knocked up in about an hour last year from pallets, with a chipboard racing shelf 6" off the ground and a chipboard top. It will cope with 300 kg green oak beams plonked on it, no problem. Won't win a beauty contest. Net cost £0. (in fact I'm in the money as I avoided taking the stuff to the tip).
Edit
I bought a complete lorry load of sawn oak from France a couple of months ago. A lot of it was delivered on very large pallets that the timber yard had knocked up especially for the job (made off loading much quicker). All made entirely of oak. A lot of it was better than stuff I have seen in timber yards round here lately!