The good news is you are not nearly as hosed as you think. The bad news is you need a new tax person. If, as you say, you never saw 1 penny of actual profit, then you really have little to worry about.
In your example you do not have $1150 of "income" because you forgot to subtract what you paid for the boards. If you paid more than you received, then you will take a loss (which is a good thing in your case).
You do not need to figure out how much you paid for each individual board, or even how much you received for each. Just add up the total you paid for everything and put it on line 36 of Schedule C. The total amount you sold the boards for goes on line 1. If line 36 is greater than line 1, no taxes!
I'm oversimplifying a bit, but the bottom line is get a good tax person and don't let it worry you too much.