The best event I attended last year was the innagural Open Hardware Summit held just before Maker Faire NYC.  Tickets are now on sale for the 2nd annual Summit which takes place on September 15th.  Priced at $50 for "starving artists" (students, artists, non-profits) and $95 for everyone else.  Sponsorship starts at just $300 and includes a free ticket along with your logo on the banner, website & program.