Mwave offers the Gigabyte Ultra Durable 4 Classic microATX Motherboard for AMD Processors, model no. GA-F2A55M-DS2, for $51.99 with free shipping. (MacMall charges the same.) That's the lowest total price we could find under $1. It supports up to 64GB RAM and features one PCI-Express 2.0 x16 slot, one 24-pin ATX main power connector, four SATA 3GB/s ports, and eight USB 2.0 ports.