Well I have extrapolated from div reinvestments back to some semblance of original purchase. I do have pricing available prior to 2003. I am awaiting American Funds, and Touchstone (started as PHBG, Old Mutual Fund, Touchstone) and I believe I am on the right track.
Luckily I can modify the 1099 to the costs at least with a 2/1 drop dead date so as to not reek havoc to the download with just proceeds and no costs.
Amazingly, with these funds in question, held for 20 + years, and the rule of 72 it turns out a return of slightly less than 3.5%. That is your investment advisor at work. We caught so many improprieties and even contacted FINRA, which as usual totally worthless.
