Spent 2 days in Xian in April under the care of Jane, her email firstname.lastname@example.org.
Her charges are 450 RMB per day plus car 4500 RMB or van 550rmb per day if required, plus your entrance fees.
My wife and I enjoyed her company, she is bright has excellent English skills, knows her way round Xian and also goes into interesting detail re the sights and places you visit.
We found her to be a highly entertaining and skilled guide and would recommend her.
Xian has more then the warriors and is worth at least a 2 day stay, we found the Banpo Neolithic Village, Shaanxi Museum and Temple of 10 Immortals well worth a visit , that is in the addition to other sights.