A 1050 4gb vram is not rare at all. Is just a laptop version of the gtx 1050. I was interested to find out that this fact is unpopular. There is a huge misconception that any gtx 1050 with 4gb is a TI model, but the reality is that there are so many models of each of the gtx 10 series that aren't ever really promoted. You only find that out once you attempt to buy a new card.
Recently I was looking at a 1060, and omg, I wasted a whole hour looking into the differences of the following sub-models: GV-N1060G1 GAMING 3GD, GV-N1060G1 GAMING 6GD, GV-N1060G1 GAMING 6GD V2, GV-N1060IXOC-3GD, GV-N1060IXOC-6GD, GV-N1060WF20C-3GD, GV-N1060WF20C-6GD, GV-N1060XTREME-6GD. Yes, these are literally 8 different models, or if you wish 4 different models for either 3 or 6gb vram, of the same general gtx 1060 capability and performance. The one is specially overclocked, the other one is a mini size model, the third one is a budget choice, and the forth one is.. extreme...everyone loves to wait for and discuss this one ..(I stopped caring). Not to mention the amount of these models triples at least (so 8x3=24...), as we get them produced and optimised by GIGABYTE, ASUS, EVGA, MSI, and one more name I forgot.
The performance differences are fairly insignificant to matter, and the pricing differences in my opinion are ridiculous (taking into account that here in the UK, an extreme version can be found to cost as much as a regular 1070 8GB) ...k.