Just to answer points raised about the value of e-mail lists.

The lists you find on eBay and elsewhere are inevitably one of three things.

Ancient - and therefore 99% worthless but at least avoiding some spam laws/regulations.
Fake - using generators that spit out words@domains.com e.g. hobnob@aol.com and therefore any that turn out to be correct are breaking spam laws/regulations.
Trawled - using software that, in effect, spider Web sites for any and all e-mail addresses, so much the same as fake lists they break spam laws/regulations.

A legal e-mail list needs ideally to be double opt-in or at least single opt-in. The first part of the opt-in process involves checking a box agreeing to receive e-mail... not unchecking a box if you don't want to receive anything - this is called opt-out.

To make the list double opt-in an e-mail is sent to everyone registering containing a uniquely coded URL for the user to confirm their membership and/or desire to receive e-mail.

Targetted opt-in lists can be very valuable through renting, though costs have come down quite a bit now. The more data a list contains the more potential value for targetted advertising.

When I was at freemoney we rented our lists for as much as £350/000 with good targetting, e.g. 30-50 year olds earning over 30k a year that had at least one credit card and had bought goods online before. With 10,000 members fitting this criteria this was a quick 3.5k for a single mailout.

Less targetted mailouts still commanded around £150/000 - and remember, this is to rent not to buy.

Take a look at a company like myoffers.co.uk - Their core business model revolves around their e-mail lists and it anables them to maintain a nice office in a nice location and to employ 25+ staff, (there was that many people working there last time I met with them anyways). Their list numbers in the millions so lets say they rent it out for an untargetted e-mail at £100/000... with just 2m that's worth 200k just for a single mailout...

Of course it's not THAT simple. Advertisers don't often want to send 2 million e-mails at once, (though some do), so list income is made up in smaller chunks.

Then there's CPA deals, which are bad for list owners/brokers. CPA = Cost Per Action/Aquisition where the advertiser gets to send out millions of e-mails and only pays on results, which although heavily in the advertisers favour still provides revenue for lists.

There are some huge companies out there whose sole business is list ownership or brokering. Take Claritas and Consumail as examples - initially they just brokered the lists of others and still made a very nice income from their commisions. Experian is another example of an absolutely huge company that makes its money from personal data - your personal data.

There's also Market Resarch, which we, (freemoney/vpanels), pioneered as being viable online and which can bring in some very nice revenue. One company used to pay us £4 - 12 per complete depending on how specific the target audience was. MR also had much better response rates... With direct e-mail advertising you can expect a response rate of <1% for untargetted mailouts and <8% targetted. But with MR we sometimes had as much as 35% respond with 90% of those going on to complete the survey they'd been asked so we could send out 10,000 e-mails and get a return of upto £37,800 though in practice there would always be a cap on the number of completes required - usually 1,500 or less... It is widely accepted in the MR industry that you will get the same results, +/-2%, from asking 1,000 people a question as you will from asking 10m, so long as your panel demographic is a broad enough representation of the population.

So basically, what I'm saying is that a double opt-in list IS worth a lot of money and the more data attached to it the more it is worth.