According to wii.qj.net, MH3tri won't have pay to play.
Via Nintendo Everything
Nintendo has some great news for prospective Wii hunters. The company today announced that there will be no online fees for Capcom's Monster Hunter Tri when it hits North America.
Instead of the pay-to-play model used in Japan, the localized version of Monster Hunter Tri will have free online and WiiSpeak functionality. The game'll come out in North America on April 20 in two flavors: as a standalone game for US$ 49.99 and as part of a Classic Controller Pro bundle for US$ 59.99.
Those who pre-order Monster Hunter Tri from GameStop will also be able to pick up a demo disc on March 8. The disc will come with two quests. pre-ordering will also net Wii owners an exclusive Monster Hunter Tri Wii Points card worth 500 Wii Points.
i kinda want this game