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The benefits of having a web site (that can be found) should be obvious.
It is a non-sleeping PR agent, sales person, receptionist, information bureau, booking agency, shop, message board. It is a billboard that only you advertise on.

It gives you as much chance as your largest competitor to attract passing trade.

MARGINAL COSTS
A web site is an investment you pay for once that repays for ever.

In already-efficient organisations, major improvements are measured in single-digit percentages.

In the Voluntary Sector, the difference in administration costs as a percentage of spending between 26% and 24%, is the difference between receiving a grant and not receiving a grant.

In the UK, 40+% of households and 90+% of organisations are connected to the Internet.
Consider the benefit to your organisation if, say,:
30% of misdirected queries never reached your switchboad.
30% of the people who telephoned knew who to ask for or could dial direct or e-mail.
30% of your job applications did not come near your switchboard or mail room.
30% of requests for information or promotional or technical material did not involve your switchboard or mailroom.
You could reduce printing of such material by 30%.
You sent quarterly newsletters as monthly e-mail and reduced printing of paper newsletters.
You could recruit just 2 more customers or 5 more volunteers without cold-calling.