Start by auctioning O and B. Top Hat will grab them to make ABOVE and BELOW.
D and G should be next, to make DWARF and GIANT.
N and U should be next, to make INNER and OUTER.
L and L are the next letters, to make LARGE and SMALL.
B and W are the next pair, to make BLACK and WHITE.
B and K come next, to make SOBER and DRUNK.
NORTH and SOUTH are the next words, using N and U.
Then comes CLEAN and DIRTY, using C and Y.
Now you have four letters and two bidders. The words to make are RIGHT and WRONG, as well as QUIET and NOISY. But don't eliminate one person right away. The last letters to go should be in this order: R, Q, G, Y. This will maximize the bidding to get you to the three million needed.