If you really like them, I would invest the time or money to have them altered. Check the care/fabric label first so they don't shrink when cleaned
after they are altered, i.e. prewash if washable.
Check & compare major stores on line. I googled curtain lengths, & this is only one site that came up.
curtain lengths - compare prices, research products, save money at Become.com
If you have an Anna's nearby, their prices are very reasonable.
Don't laugh (okay you can laugh if you want to
), but depending on your decor, I've found some interesting window treatments below. Some can be cut down. i.e. these string curtains (etc.). There are some interesting styles. Have fun.
String Curtains, Fringe Curtains, String Curtain Panel, Fringe Curtain Panel
(Saw an entire wall's length of these on HGTV, & the "look" was pretty cool - allowing the light in -- if you don't need total privacy.) I've ordered from them before, & have been very pleased.