These little guys are lighter and cheaper than the Stans tubeless valve stems. They have removable valve cores and weigh only 3g each. They work well on Podium MMX rims with Stans yellow tape. The large o-ring on the stem is soft enough to conform to the curved inner profile of the Podium MMX rim. This inner profile is the same as the Crest rims so they should work equally well with those rims.
Get these for around $12 on Amazon.