I usually buy from local breeders/rearers or other TAS folk, mostly successfully tho one friend brought me 4 pols that were 2 white leghorn and 2 Menorcan (or so I surmised, the breeds he didn't know as he'd bought from the breeder without asking!! And 3 of those were stupid, refusing to go in the coop, roosting in too low bushes rather than with the other outdoor roosting hens up in the Scots Pine, and the fox got 3 in one weekend when I was away. The last hasn't laid since, and is a very light hen compared to all my various other breeds/hybrids, and despite being very flighty (probably what saved her) she is the one that can get in the cat hole and roosts on my kitchen surface/pan rack if not found and booted out at night!
Oh, I also bought a pen of 4 POL Copper Black Marans at Lanark mart 18 months ago and the 3 that I still have are really nice birds. I'd tried many times to get Marans from TAS and locally with no success so just went overboard and bid which is something I enjoy but am probably best not doing too often!
I tried hatching with broodies here a few times but mostly without success in terms of getting POLs for free. So am going to try rearing from day old next, if I sort out the practicalities and costs. Other than that I'll go back to past sources for more when I need them.