Marketing for a wholesalers show

Hello -

I will be exhibiting at a wholesalers show which is held at the end
of July and would like to send out postcards marketing my jewelry.

If you have tried this type of marketing before, would you be kind
enough to share your experiences?

How far in advance of the show should I send out my mailings? Should
I wait until a week or two before the show so that it is fresh in
their minds? Or should I send it out as quickly as possible even
though the event is not for another 2 months?

Also, the organizers are offering a mailing list of attendees, but
its very expensive. (over $1000) Should I purchase that list? Or do
you think I should just purchase a mailing list from the Jewelers
Board of Trade? On the one hand, the expensive list is more precisely
targeted. On the other, its very expensive. What do you think I
should do?

thank you,
Phillip Sung