Most of my curtains are cloth tablecloths. I've been doing it for years. Tablecloths, rectangular ones, are not that expensive and you can find them in a variety of patterns and colors. I am into more vintage, colorful decor, so they have been a perfect fit.
Rectangular tablecloths come in a variety of sizes, which make it easy to fit most windows for a price that is cheaper than buying large curtain panels. Most come in a size of 60"x84" which is what most long curtain panels measure.
I will look online for ideas of what I would like, then browse local stores or Amazon.com. I've had a lot of luck at Target. Look for ones that are only fabric and no plastic backing.
Here are my dining room "curtains" I found at Target. They cost me 15 bucks a piece. They fit in perfectly with my dining room.
All you need are these, (drapery clip rings) and voila, instant curtains. Just space the rings evenly on the top of the tablecloth and hang on the curtain rod. Easy peasy. You can find the drapery rings at a store that sell home decoration items. Walmart, Target, K-Mart, etc. They will run you $4-10.
You can buy new long paneled "curtains" for $30-40 bucks. A fabric shower curtain will also work for small windows or if you do not want your curtains to touch the floor.