It's because Wheelie was short-packed:
2 x SPRINGER
2 x SWERVE
3 x CLIFFJUMPER
1 x WHEELIE
Not sure why, but I guess Hasbro HK thought that Wheelie was such a hated character, that it would have the least demand. And it may well be, if the Singapore fan-forum is reporting it to be shelf-warming despite its 1-per-case ratio.
RobotKingdom has restocked the deluxe figures, but the Voyagers are still sold out at the moment.
I picked up all four, Cliffjumper is $22 and Wheelie is $35 to account for their relative rarity, with the other two being $30. Figured this way I know I've got them, and if they came to TRU, they're likely to be the same price anyway.
The Deluxes have been found in Canada retail. The GDO figs may not so hard to acquire after all. So much for Asia(n) exclusive....