@lukhuleni, i know motors/reducers and also shredders are not much a big problem in southern Africa. Electricity to some degree yes. I would recommend contacting existing recycling facilities first, afterwards, any machine/metal working shop. I could even imagine to make the shredder with an angle grinder and a drill press by drilling along the edges, out of sheets and solid square bars…takes some time but possible.
Prices all vary depending on how and where you get the parts you need for the machines and also labour. if you are skilled in welding or have someone to do it for free,it lowers your costs. Also if you use parts from a junkyard it will lower costs.
in Europe for example, I would say each machine can be built with €1000 (purchasing new parts and including labour)
Start with the parts lists and try to find out what prices locally you encounter