I'd expect that Etrade would have the correct numbers in their supplemental information, but you should always verify that information, which is easy to do. Your per share basis should be exactly the same as the per share "fair market value" used by your employer to calculate the compensation created by the vesting of the RSUs:
Compensation = (GROSS number of shares in grant) x (per share fair market value used by employer)
The compensation should be disclosed to you on your W-2 and you know the gross number of shares in the grant so simple math will tell you the per share number used.
