Remember for a lot of veg you only need 6 inches of highly fertile soil9 I was very surprised till I started to practice this ) to grow them in.
So you can fill the bottom of a raised bed with a poorer soil .. even to putting in a layer of rubble if the beds are that deep & blind it with the poor soil . Then put down a double layer of weed suppression fleece , then add the 6 inches of quality soil that you either beg , steal , buy in ready made or make up as per a John Innes type formula it .