I buy reels of bare copper wire for the same price as aluminium and anneal it myself. You can just buy wire on ebay, amazon or other online commerce websites. Coil smaller gauges of wire and make straight lengths of larger gauges then anneal them in a wood-burning stove by heating until cherry red and letting them cool in the air.
Attached is a chart for converting awg to mm and inches that may come in handy.
