Frames are SO expensive, but this is an alternative. Use floor moldings (they come primed, just paint whatever color you want), construct them to fit pictures (like Costco's basic poster size). These frames are 20x24.
Transform a basic $39 Ikea STAVE mirror from blah to amazing by mounting it on to a piece of plywood with ornate moulding. Best of all... the STAVE mirror comes with brackets that allow for your mirror to open when mounted on something. The mirror now conceals my costume jewelry necklaces from being seen!