DIY blackout curtain liners. Buy blackout curtain liner from fabric store ($6 a yard). Cut 2 panels 2 yards each. Hole punch and hang with shower rings. Hide behind grommet panels! SO much cheaper than blackout panel, especially if you use a Joann fabric ap coupon!
How to (and how NOT to) paint curtains to get a custom look without a custom budget. Curtains for oversized windows can be expensive, but starting with IKEA curtains and then adding your own design can save TONS of money.