If you pull a standard title report, it will show the last three sales. If you need a more detailed one, I can put you in touch with someone to do that for you.
Also, you may want to check escrow documents or title documents that may have that information listed as well.
Unfortunately the MLS does not maintain data that far back. I know a client of mine paid an appraiser to do a similar cost basis calculation. I am not sure what it cost. Maybe a Title Company could also provide the information, I am not sure. I hope that helps.