Calculating appreciation based on rehab dollars put in.

Hi everyone!  I am interested in buying a small multi-family, doing some cosmetic work, renting 2 units and living in the 3rd.  How much will a property generally appreciate for every dollar put into the property?  I would like to spend around 15K on the rehab, if I focus on items that really drive value how much appreciation can I expect?  20K? 25K? 40K?  Any and all help would be awesome. Thanks!!