Can b1,b2 visa holder apply asylum and if yes how much would attorney cost

The issue is whether it is within one year of your entry into the U.S.  Also, what are the facts and how much evidence exists to prove a "well founded fear" of persecution on account of one of the reasons allowed as a matter of law.  Sometimes, people begin the process and become targets for deportation when there were other better options available to them. As a result, fees are best decided based upon whether the intending asylee can overcome the burden of proving that they deserve asylum as a matter of establised law and decisions.  If not, then the alternatives ought to be discussed and the matter left alone.  A more unsubstantiated claim will take more time to prove to the satisfaction of either the asylum office or the Immigration Court deciding whether to deport you for eventually overstaying your B2 visa. This will happen where USCIS denies ("refers") an asylum application to an immigration court known as the Executive Office of Immigration Review!  As a result, I strongly recommend a paid consultation with a competent and experienced immigration attorney before you spend thousands of dollars.