Valuing an Internet Business - that old chestnut

[Dave2P]

Been helping a friend out who has an investor interested in his business; both see big potential in building out from where he is at the moment - for which it'll need investment.

Investor wants a minority stake (prob ~10%, maybe a bit more), and brings good contacts and experience into the mix.

Background is; business always in profit and with 6-figure turnover for last 7 years. Website traffic is several Million annually.

So how do they value the business? Any common rules-of-thumb?

I know, I know; how long is a kettle of fish? how many Instagrams? etc. but any pointers as to where to start negotiations would be very much appreciated. Thanks in advance for any input.