These are on close out by volquartsen (and can be found on the VQ website as well). Note that this kit does not include the VQ bushing as it’s designed to maintain the MKIII style hammer and bushing for those keeping the mag safely (why someone would do that beats me). However you can buy the stepped tandemcross bushing for $10, to use with this kit and delete the mag safety. I let this sit in my cart a few days and the seller offered 10% off, bringing the price down to $54 shipped. I have several of the mkII kits with the VQ bushing and this one is feels comparable dry firing (though full transparency I’ve not yet shot it due to the fire danger). I am using the tandemcross bushing with this kit and have no issues with the fit thus far.
https://www.ebay.com/itm/224079136615
https://www.ebay.com/itm/224079136615