PennyStockTrader2, i traded with with TDA 10-15 years ago.
still have the account, but now trade via my Etrade acct as i like their tools better.
so i can't confirm that TDA can trade XCLK for flat commissions.
but i can confirm Etrade will.
i have bought & sold 20m lots of XCLK via my Etrade acct over the past few months (flipping btwn 0001 and 0002, while accumulating in the process), and my commission has always been $10 regardless of lot size.