With those paint problems the presentation of the car is not the best, the first thing a potential buyer will look at. You don't say where you are but I suggest compare what other Mazda 3's are going for in your country and the condition they are in, price it accordingly.
At the end of the day it is worth what the market is willing to pay for it, is the inspector going to give you money for it? I would suggest trying to sell it at around $3000 and let a buyer negotiate with you for a good deal so everybody wins. It might take a while to sell but be patient.
I know how you feel I recently had to get rid of my MX5 and regret it everyday. Good luck I hope you get a reasonable price for it.
RE: Selling the mazda