You could get a chassis for about $5k from various fabricators, DOM, welded, proven designs.
If you want to go the buggy route, I'd keep your sammi and use it while you build a buggy, then sell it when your done and recoupe that at the back end.
Do a basic 5.3 v8, Manual Valve body th350 or 400, a 3.8 atlas, Built 60's or 9's, and BFG stickies.(10-15k)
Drop those parts of with your fabricator, and they can send you back a roller, for about 10k.
Then finish it yourself with another 5k in misc parts and a couple hundred man hours.
Total 25-30K.
You could buy a good one for around 20 if you waited for the right deal.
I'm all for Buggies, but make sure that's the type of wheeling you want to do, and you don't waste your time building something that doesn't work and you aren't happy with. Elbe, and Evans leave a lot to be desired when wheeling a buggy, and you'll find you need to drive a bit farther to go somewhere with what i would call "buggy" trails. 2-3hrs.