Pick three, six or nine photos and blow them up to the same size.  Print them in black and white or sepia tint.  Frame them in same size frames in black or brown.  A 12 x 18 inch frame from Aaron Brothers costs about $18.  I would suggest that you pick a standard size frame first and then print your photos to fit.  If you already have several frames (recycle) paint them the same color for a pow-y look!  Your cost will be around $6 for the paint plus the cost of the prints.

A fantastic way to decorate very, very inexpensively is to create your own art.  Buy old calendars that have themed pictures you like.  I recently found some for $1 each, regularly prices at $13.95 at Scrap.  I have used Picasso, Landscapes and Botanicals.  You can buy a wonderful craftsman style frame for about $18, add the appropriate size mat, and away you go!  Do a collage of three, six or nine for maximum impact!  Hang in an entry hall, over your sofa, above the mantel or over a buffet.

I recently found a rectangular frame and a frame with an oval cut-out at a thrift store.  They nested into each other, which made a big impact!  I inserted a gorgeous greeting card (I save them all) and, voila, a great addition to a bedroom wall!  Reduce, Reuse and Recycle is my mantra!  Cheers!
Eco-friendly+Eco-nomical=Eco-fabulous!