[KathyC]

I'd guess those are 6 x 6's in the pic. Take a look in the yellow pages under pond/pond supplies to find someone local to you. The liner material is usually sold from rolls, and frequently they carry it in different widths. Get the thickest EPDM material you can afford.
Another option is to purchase a 'pond kit'...HD & Lowes carry them at the best prices. They come in a variety of sizes and usually include the liner & filtration system and sometimes the underlayment. (please do not skip the underlayment, it is critically important in an installation like this).

Are you going to use it as a grow out tank, for spawning or simply viewing?

I'd suggest you go no higher than 30 inches or it is going to be a pita to clean. I would also skip the bottom drain (asking for trouble indoors) and use a Python to clean it, get some light-weight rigid tubing to extend it, or buy the Python Ultivac (approx 47.00).

Yes, I have an outdoor pond, and yes I had to build a temporary indoor tank last year for my Koi. It was 4' x 4' x 30".