I created a spreadsheet with a square root fitted to Gox/Bitstamp concatenated price history.
Here's a link to the spreadsheet
https://drive.google.com/file/d/1rBFpga3tLH2Lkac1YuvF-xQgjSDoWR6Y/view?usp=sharing

E3=0.0913388*A3^0.5-1.51936

edit: below, charting price with respect to the sqrt baseline.

Interesting work!