[jacquesm]

Those other people that are doing this right now in their crappy way in a sense already validate your market.

Can you figure out how large they are (alexa, compete), can you make a stab at their conversion rates ? That should give you (with some room for error) an idea of turnover at a given size. Then look at how long they've been doing it, that will give you an idea of the 'runway' you'll need to get to that level (or any intermediate level).

hth

[jeer]

Thanks. I hadn't considered using the age of these other services as any sort of indicator.

[jacquesm]

Conversion rate is the hard one to estimate, you could easily be off by an order of magnitude or more.