refrigeration supply store or home depot... im gonna run stainless steel you can get 20' lengths from summit look under tubing they have 3/8 and i think 1/2 inch somethin lke 30 bucks for the roll MUCH CHEAPER THAT COPPER
^^^ why, I get lots of things from HD. Yeah I don't buy my bags or compressors ther, but basic things like grade 8 hardware work just fine. I'd run stainless cause it looks good polished, but copper works too.