I've seen a lot of people replacing their master bathroom mirrors with 2 smaller framed mirrors. It always looks great but I've also seen people just add a frame to their existing large mirror.
The cheapest frames that I liked were around $50 each - plus we'd have to fix the drywall if it came off with our mirror. And buying a large frame would also cost at least $100.
We went to Lowes and bought some crown molding for $40 to make our own frame. My husband glued, screwed and clamped the crown molding together over night to make a frame.
Then I sanded the corners down and used the rest of my Rust-Oleum Cabinet Transformations from my cabinets to paint it.
LOVE how it turned out. I'll have pictures very very soon! :)