Sperm banks simply do not cater to transhumanists. They first and foremost screen donors for sperm count (to insure that they can make the most money out of every stored sample). Sperm count isn't strongly correlated with intelligence.

After sperm count, important factors for sperm banks are: Physical health, height, and weight.

Plus, sperm donors are mostly a self-selected bunch, and I'd guess that men who are in no immediate need of money would not wake up in the morning thinking of donating sperm.

Finally, upbringing is probably a far more important factor than mere genetics; a wise mother would want to ensure availability of the father for childrearing.