The great thing about building your own forge is that you can tailor its dimensions and function to you, your workspace, and what you're forging. A JABOD forge is cheap, easy to build, and (perhaps most importantly) easy to modify. If you're building it with salvaged materials, your only investment is in time -- and it's time that you're learning, so it's never going to be a wasted investment.
When I switched from my old rivet forge to a JABOD, not only did I get a much more functional setup, but I was also able to turn around and sell the rivet forge for about what I'd paid for it, plus a decent leg vise. If I were you, I'd give a JABOD a try. If you prefer the forge you have, great. If not, you can hang onto that forge for as long as you like, or you can sell it. With decent legs, I imagine it would bring decent money, which you could then spend on other fun stuff.