By the way here's the total cost of my new 48qt mashtun on the cheap side : 43.50 CAD.
20$ + 7.50$ hardware + 16$ bazooka screen. Not bad for a 12 gallons mash tun! I skipped the weldless bulkhead (too expensive) and replaced it by a couple parts from my hardware store (a 1/2 short nipple, 2 washers, some o-rings and 2 pipe nuts). I did go for a plastic ball valve since I didn't know what a metal valve would bring.