I'd check these sources;
www.donhume.com www.highnoonholsters.com www.blackhawk.com www.Bianchi-intl.com www.galls.com www.mitchrosen.com www.epsaddlery.com www.miltsparks.com www.safariland.com .
The High-noon skin-tight line has thumb break styles but is a man made leather type material. They have 1911a1 models ready to ship. Some smaller shops may take a few months. The black leather Blackhawk rigs may suit your needs but many handgun owners like the SERPA holsters.
El Paso Saddlery has a few great leather strong side thumb-break holsters in the $75-80.00 range,
. Don Hume is a good value too and is in use by many working cops & security officers.
Clyde F