[jhv48]

I believe your price ceiling has ruled out both ERA and SPF for brand new builds. Used, will open up all three for your consideration. Both of those makes (ERA & SPF) will probably cost more than your $70k ceiling to build and license. That leaves BDR.
Check out their website and see what you can get for your $70k.
If you're willing to consider a used cobra, then for $70k you will have lots of choices.
You can't go wrong with either of the three makes.