These guys,
If you want to spend some money, below are two where you can purchase UPOCC solid core silver by Neotech in bulk. I do not know of anyone selling solid silver in fine strands.
VH Audio also sells solid core OCC silver in a variety of sizes up to 14awg.
http://www.homegrownaudio.com/categories/Solid-Core-Wire/Bulk-Silver-Wire/?sort=pricedescsell 10awg solid core either bare or in FEP and also a 16-strand, 22awg per strand, which would equal a 10awg if you used the whole braid. If you wanted 8awg, you could twist four of the 16-strand bundles together and connect them in a star-quad geometry. I would probably not use them for power cables because of the FEP covering.
If you want to spend some money, below are two where you can purchase UPOCC solid core silver by Neotech in bulk. I do not know of anyone selling solid silver in fine strands.
http://www.partsconnexion.com/wire_hookup_neotech_silver_teflon.html
http://www.liveacoustics.com.sg/upocc.htm
VH Audio also sells solid core OCC silver in a variety of sizes up to 14awg.
http://www.vhaudio.com/wire.html