Please Help: Acceptance of Govt. Audit Before Taking NOC From Previous Auditor

i m doing audit of NREGA Gram Panchayat for F.Y.2009-10 @800/- Per Gram Panchayat.and submitted the bill. for the F.Y.2010-11 Zila Panchayat Invited Tender for allotment of Audit. various CA Firm are Applied for this and quote Less fees i.e. below 800/-. i want to know that can the firm take assignment in such below rate and i also want to know that can a CA firm accept assignemt before Getting NOC From Me.