Why do I suspect it is a fake:
1. There are fakes of that model circulating around, so it is possible
2. The BM insignia is missing from base of the blade. From what I have seen pictures of the real thing, they seem to have BM insginia on one side and serial numbers etc on the other. Most people would take a picture with the insignia shown if there was one the blade. Not that the logo proves anything, since it can also be fake.
3. All the 49-03/steel I could found sold did not come in that basic blue BM box, but rather had a more upscale box
4. The asking price seems low. From what I found out on net about the 49-03/steel version, it seems to be a limited edition thing. Prices ranged from 400 USD to 1700 USD. The starting price is 100 USD and buy immediately price is 150 usd. Perhaps this is some cheaper non limited edition version of the BM 49-03, but I could not find such examples from the net.
5. The seller claims that the product is new/unused, but is not able to come up with receipt etc.
There are three possibilities
1. It is a real one, albeit not the limited edition model and all is good.
2. It is real limited edition one and the seller is not aware of that --> all is very good
3. It is a fake
There is no evidence show far for 1. and I do not believe in Santa Claus (2.), therefore 3. seems a good bet.
I have asked for additional picture, but lets see.