You can't really estimate what material you need until a design is at least semi-finalized. The type of material that you need will start with channel or box steel for the structural bits (at least 1/4" wall thickness) and 3/8 - 1/4" flat mild steel for linkages and brackets.
There'll also be wire, switches and connectors for an electrical unit, or all of the hydraulic lines, fittings, and such for that type of power, along with misc. nuts and bolts.
Then there are the tools that you will need to buy or rent, such as a welder, chop saw, etc..
Whether or not your budget will be adequate will really depend upon your shopping skills. A local scrap yard or auto wrecker will probably sell you used steel for a reasonable price. Even a manufacturing outfit might, since they get it pretty cheaply in bulk.
I'm once again in the position of trying to respond while getting ready for work, so I'll have to leave any 'figgering' until later.
By the bye, how much pressure does it have to exert in the mould?