I went to a SWAP at a Local Feed Store in Albuquerque when I was on vacation a few weeks ago. The organizer told me that New Mexico doesn't require any health certificates, flock testing, or licenses to sell at public venues. Everything there was pretty laid back in that no one kept track of who was selling birds or what they were selling etc..
To sell in Texas your flock must be P/T tested to sell from your backyard and an addition license is required to sell in public places like a
TSC SWAP, Flee Market, Poultry Show, etc. I just had the inspector for the license to sell in public venues come to my place and am working on my $35 application he left me to mailed to Austin to be processed and returned.
The inspector for the license to sell in public venues told me when he came by that I would have to keep a customer list of everyone that I sold to, what I sold, where I sold it, and when I sold it. The casual atmosphere of the New Mexico SWAP would not meet the Texas requirements. The Texas State requirements are not difficult to meet. The P/T test is done free of charge to the flock owner, and the 2nd inspector for the public sale license only records your GPS location and the size of your flock. A
TSC SWAP should be fairly easy to set up, but it would not be open for every one to sell like in other states. The organizer would have to verify that anyone selling had a license to sell in public venues.