Create a iifym meal plan.
Neck a 1500 - 2000kcal home made shake. Don't by gainer shakes or expensive whey, purchase blend whey then mix it with home ingredients [pea-nut butter, milk, oats].
You should be aware of cheap sources of protein [fish, chicken, minced meat, pea nuts, milk, pie and cheese]. Cheap source of carbs [rice, pasta, spaghetti, pie, bread and oats]. Cheap source of fats [burgers, cheese, nuts, pie, pizza and oils].
I find it only gets expensive when ones wants to cut. Cutting removes the flexibility you once had.