To me most rounds that I see for sale seems very cheap when you compare them to buying another type of business, the two extremes I've seen are the guy on dragons den the other day that sold a £6000 a month round for £16000 and then theres a round for sale online, £9000 a month, asking price £100,000.
To me your buying/selling a business, not just a round, and all your hard work. Obviously your round/business is only worth what someone will pay.