It all comes down to how much you're willing to pay for a stand. Looking at my SS stand, the I'd estimate that there's significantly more resin in the stand than there would be in a bio. Now, because it's a simple pour job, it wouldn't need to cost as much because there's not as much time spent making it.
I've seen those stands, and I think he's charging $80 per stand? That's probably at the low end of what anyone would be prepared to charge for one. Then there's shipping on something that weighs about 12lbs. Within the US, you're talking another $25 right there. Then you need somewhere to put it...you don't hang 12lbs (+ bio) on your wall lightly, although yes, you can put it on a shelf.
It could maybe be done in 2 halves with fiberglass and then pieced together, but that would be a lot of work, and although materials costs would be lower, labor would be much higher.
Finally, the SS stands don't necessarily accomodate all the different styles of bio, which all have different forehead slopes and would all need to sit differently, therefore needing some adjustment somewhere to display them right.
Not saying it can't be done, but frankly given that it can be difficult to persuade people to part with $140 bucks for a bio, who's willing to pay $100 or so just for a stand?