if the tank is already drilled then you don't need to get overflow box, a pump is going to run you around $100 depends on what GPH are you looking at, I got my mag drive 12 pump for $99.99. if you need over flow box then depends on what brand and flow rate, price varies.
as for plumbing you can go to homedepot or lowes for PVC pipes and fittings those won't cost you much.
you just need to figure out the flow rate of your plumbing before you decide on a pump.
as for plumbing you can go to homedepot or lowes for PVC pipes and fittings those won't cost you much.
you just need to figure out the flow rate of your plumbing before you decide on a pump.