What would you pay for a Wilson Combat sling shot? I would not pay what they are asking for it. It will be on clearance for 75% off in a year. It will still be too expensive.
Here is an alternative to the Rare Breed. It doesn't say if it works with large frame ARs. Trigger groups are the same. You should be OK if it has the correct type of bolt carrier.
https://partisantriggers.com/the-disruptor/
Being from Texas, I am partial to Whataburger. I may need to check out In-N-Out if this is accurate. I found it on a post by Firearms Policy Coalition.