Maybe it's already sufficient for your application to sort the individual triangles back-to-front.
You can store the vertices statically on the gpu and issue a sorted list of indices in every frame,
for example. It's not too bad.
If you really need perfect transparency you may consider depth peeling.
It's a multipass technique and runs on older hardware.
The cheapest trick is to draw in any order and tell everyone it's correct.
Most people don't notice alpha-blending errors anyways