Optimum fees for accounting of a proprietary concern

Hello,

I wanted to know the optimum fees that should be charged for maintaining Accounts in Tally of a Proprietary Concern with about 70-80 purchase bills, 50-60 sales bills(both purchase and sales contain VAT) and about 120 bank entries(in a single bank account maintained by the proprietor) along with some other expenses related bills paid in cash. The nos. given above are annual.

Please give me some guidance as to what fees can be charged simply for Accounting. I'm looking for figures! Thanks!