thats why when ever you sell a car privately you always set the asking price about $500 more than what your really looking for. so that way you already have that as a buffer to drop the price.
makes the buyer feel like they got an even better deal and you still get close to what you want out of it.
also if they are seriously asking for $2500 off. there may be a reason. what are you asking for the car and what is the kbb value. most people wont come out and say "your car isnt worth that" so they will look for reason to cut the price like crazy
as well if you are around the kbb and they want $2500 off seriously for tires and brakes ask them where they think brakes and tires cost that much. as a seller you are only resposible to replace with oe rated parts. dba or hawks are not in that category