Get the cheapest 14g speaker cable you can get that's 100% copper - if you go with copper clad cable go one size up (12g). Monoprice has good prices but there are other sources.
For 703 you may try a drywall supplier. If you can't find any and are on a budget, I've seen people use other material including Armstrong acoustical ceiling tiles.
7.4.4 Theater Room: JVC-RS500, Silver Ticket AT 2.35:1 142”, Onkyo RZ830, Anthem PVA-7, Panasonic UB420, Apple TV 4K, JBL Studio 530’s, 4 - 15" DIY Sealed Subs
3.1 Living Room: Samsung 64” F8500 Plasma, Anthem MRX 300, Dynaudio Audience 52’s, Dynaudio Audience 122C, NHT SubOne, Roku Express (2019)