I highly suspect this frame is one of the group that showed up on EBay a few years back. (as BlkHawk73 mentioned) I also bought a pile and have a couple left.
I had some correspondence with the seller but he was keeping info very tight as to whom, why & where the Mfg.
They were cast to just about perfect fit on the flats. So close that there was literally NO material left for fitting and finish.
They were straight, fit up was just about perfect, the ears were just a tad high, a good thing.
They need to be carefully cleaned up in the flats area, (where it meets the grip frame) keeping the flats flat where it meets the grip frame removing only what's necessary to get it to polish. The rest cleans up real easy, I fit grip panels at the same time to get it near perfect.
Overall they were some of the best cast brass grip frames I have ever dealt with, the only complaint is there is just no room on the flats.
As to Value, $200-300. Keeping in mind no one is currently making brass grip frames in XR3-RED, SBH, Bird, profiles. Power Custom is doing a 2 piece XR3, ($260) that can be cut to a Bird. I have heard rumor PC is no longer doing Brass but can not confirm.
Finally if you want a Brass Bisley, the only know source currently is John Linebauh as a option (+$1000 is the # that has been put out there) on one of his builds.
A recent build using one of these frames, bringing a OA back to life as a 5.5" adjustable sight.