Your Realtor should give you advice on these things. If you don't have a buyers agent you could pay way too much.
PS as to value, when you go to get financing the bank will do an appraisal and it will give you what they feel its worth in comparison to what has sold. That said some home have added value to the buyer, who will pay for it.
So I guess if you like the home, have seen what is available in the market, and feel it is worth the price to you, then go for it. Remember a home is not an investment, it is a place to live in, a forced way of saving money and if you make a wise choice will sell quicker in the market at the then fair market value.