Wine Fairs VS Private Wine Tastings, what is more effective?

When looking for distributors, wineries usually attend International Wine Fairs such as Vinexpo, Vinitaly, Prowein, Alimentaria.....Regional Promotional Boards as ICEX (Spain), Ubi France, are very well known as organizer of a kind of events "Meet our country wines".

What is best?  Participating at International Wine Fairs is costly effective?  How much business you need to pay off 4.000-8.000 euros to get your booth on those exibitions?  Regional Boards can get a good number of importers? is it worth to participate in regional tastings?