Reg cash on delivery

I need plugin for cash on delivery option. In cash on delivery, i need function like if user orders below Rs. 1000 – cash on delivery should be hidden, if user orders between Rs. 1000-2000 (COD Charges is Rs. 100), if user orders above Rs. 2000 (COD is Free)..may i know if there is any plugin available for this function in cash on delivery…i m waiting for your reply