Gun rest

I am wanting to find a rest for Ms. Lucy and went looking thru my shooting catalogs and out of 100 pages all are basically the same, with various degrees of quality and accessories. So I am thinking about building my own rest for her since, I have the skills I believe necessary to accomplish a project of this scope, and I am cheap like that. My wife says I will spend $100 to save $10 and I have to admit sometimes she is right, but I have learned a lot of good stuff in the process!
So let's look at what my requirements for this would be, first it should be light enough to carry fox hunting a field but heavy enough to take a 243 recoil. Be able to anchor on the bench (sand bag) and in the field, while allowing me to stay on sight with a moving target.. I guess holding the weapon rock steady while protecting the gun itself is a important consideration also. Easily and quickly adjustable to elevation and point of impact would be an important factor to keep in mind and last but not least cost no more than the cheapest one I could find in my local Gander Mountain store.
I would like to build it all from recycled materials to keep with that green thing that is so popular right now, and barter all of the work I could not do myself in exchange for my welding skills. I see some machining might be in order if I get carried away, and some sewing. I will keep you posted on my project as I progress, and think I might wander down to the junk yard and see if anything looks like it might fit into this project. You cannot be an inventor or artist if you have to buy everything new!