I am planning an amp build using a pair of TO-264 devices on the output of each channel, but am having trouble finding a matching thermal pad which is not electrically conductive. Datasheets for Bergquist suggest there should be Sil-Pads of appropriate size, but I cannot seem to find them in-stock at my usual suppliers (Arrow, Mouser). It looks like the DIY Audio Store's Keratherm pads will work, but the price is rather steep.
Does anyone know of thermal pads of sufficient size and affordable price? Is it possible to make these work with careful orientation?