Sometimes really simple solutions come along such as solid pine shelving from pound shops or even the big sheds can be a good cheap option. Many years ago I got about one and a half km of shelving board free from Ikea as long as I used it for charitable training purposes and didn't't sell it on, otherwise it would have had to be burnt. I nearly broke our Luton van with all that! We used to get a lot of pine off them as the cardboard boxes they came in were damaged!!!