I just wondering how much will my website sell for? The website has been live for over 4 years, it is PR3 it has over 280000+ backlinks. Daily traffic is around 14000 visitors a day, revenue around $150,000 per Year.
I have contacted a website broker and he told me they can sell the business for $350,000
Lol in all seriousness this probably isn't the best place to ask for appraisals of websites. Go to the professionals for that since it really depends on a wide variety of factors.
Since you already seemed to have talked to a broker about it you seem to be on the right track, but I would recommend going to multiple different ones that have good reputations not only to get different opinions on what it is worth but also so that you find one you trust and like.
It is just like buying or selling a house in my opinion. The key is to find a realtor (Or broker in in this case) that you can trust. That way you know they will work hard to find a good buyer and also have your best interest in mind.