Lets see there were a number of questions there.
I started in Aquaponics at the end of 2007 so from starting reading on the BYAP forum to now it's been about 3 years for me.
Just keep bugging the people with the water tanks I know that those business and fish farms are not always good at getting back to people so keep trying.
Another option might be liner in the ground or I've made a fish tank using fence panels and pond liner. Plastic stock tanks from a feed store can also be an option.
Turnip and collard greens. I can't say that I ever tried feeding those to the fish. Turnip greens are so easy to grow but they are really high in calcium so you might want to also offer something like parsley with them to get some magnesium to balance it. Anyway, David's advise sounds pretty good to me. Biggest challenge with feeding leaves to tilapia as making sure they don't clog up screens or pump grills. I don't actually keep tilapia anymore as they are too much trouble to keep warm when catfish grow so easily for us without the danger of dieing from the cold.