Projected Website Visitors.....

[Weenie]

Hi,
I desperately need some help and am new to the board!
I'm in the process of setting up an online business and really need to secure a supplier that I have been after for ages!
They have asked me for a projection of sales volumes and visitors but I haven't got a clue how you work out how many visitors you are likely to get before you have gone live. Does anyone know how or if this can be done and where could I obtain the relevant advice to do so?
I can tell them how I will go about getting visitors with PR, advertising, traffic and affiliation but I'm stumped on the actual figures.

Thanks for reading and I really hope someone can help
Thanks :)

[Joe89]

What do you sell? I'm just curious. Also, a lot of web hosts provide statistics based on the past hits you've recieved that estimates how many hits you will recieve the next month, check to see if you have that :) Good luck