Do you need the gas post on there? You can get a generic (non-keg) bulkhead from McMaster, but of course it won't have the post.
You can get a SS one with flare fittings for $25 (are 37 degree flares what MFLs use?)
Or a brass one with 1/4" barbs for $7
On the brass one it looks like you can go through a 0.375" wall, not sure how thick you need.