I don't have any of the products you are looking for, but I've been told that using gypsum in clay - well, it would take far to much to make any difference. Also, I've been told sand is not great for loosening clay either. During rains it separates from the clay and you end up with sand on top of clay (I know this from experience) :-(. And I don't believe either of these will help much with your nutrient deficiency. I think your best bet is to use all the organic material you can lay your hands on, and maybe try some expanded shale, green sand and lava sand to loosen the clay and to help with adding nutrients. I think these are expensive so may not be an option, especially large scale. My opinion, go for the compost and organic matter to get the best results.

Don't forget to check with craigslist.com. They often have people giving free compost, manure and mulch away.

Good luck. Sounds like you have quite the task on your hands.... If I was going to advise you, I'd say start with one corner. Something you can enjoy. Make it nice and elaborate. Then get to the rest later.

Good luck and happy gardening!

Gardenville just raised (in the last month) the price of lavasand by almost twice so it was expensive to buy wholesale for a project like this now it is downright costly and forget retail. I am not going to carry it anymore and have switched to Nature's Guide which is 50% less at wholesale so is still expensive but not nearly as bad as GV. I think there a few places that you can get the expanded shale up there (LETCO) I believe is the Dallas area supplier for bulk. Yes, organic matter is going to be your most cost effective option. Buy it by the truckload 12-15 yds. at a time to be most cost effective for the trucking charge. It will take several truck loads to do 2 acres so start with a smaller area that you want to do first and work your way out. Areas that you want to landscape this year would be my priority.
Good Luck and Happy Planting David.
P.S. I second checking Craiglist regularly and see if you can acquire portions of your needs there

There is a soil forum here--click on forums at the top of the page, then garden forum, and soil shows up on the list. A lot of folks deal with clay and have good suggestions.
As for compost and poo, is there a feed lot or auction barn near you? If so, they usually will let you scoop and carry off as much litter/poo as you want. It is fresh, so let it decompose before you plant. I have spread it directly where I want a garden and let it "rot" there.
Nightrider gave good advice--start a small bed that you can enjoy from the house and the yard, maybe even raised to get around the depleted clay problem. And when you get tired and dirty and discouraged, think how much good you are doing by bringing back these two acres. Good on you!

Hi there, sounds like a lot of good advise about starting with a small area. I live near Collinsville (teeny town- mapquest says its 50 miles from you) anyway, we have cows and lots of cow poo, old hay laying around, tree limbs and Lord only knows what else that could be shredded, chipped or shoveled in your ground. And all free. :) If you're interested in driving over to load up your pickup truck with whatever we can find, let me know!!! I'll even help ya shovel!
Email me if interested at maryj21@verizon.net