The battery can be purchased for as little as under $1.  It's a standard CR-2032 lithium button cell. You'll have to ask locally for the cost of the labor, since it appears the mainboard must be removed;  figure on an hour's labor charge -- whatever that is in your location.  
What is the cost of dell inspiron n5010 cmos only battery? And the cost of dell inspiron n5010 cmos battery with motherboard take out and in charges. Pls provide help.My laptop's Cmos battery is dead..
What is the cost of CMOS battery for Dell inspiron n5010?