I had a similar dilemma when I couldn't find an 'original' or vintage peep sight for my Marlin Model 1897 lever action .22. And even if I had found one, I probably wouldn't have wanted to pay the price for it. I ended up buying a new, blued version and it stuck out like a sore thumb on the gun. I put it in a dish of white vinegar and in about 30 minutes I had a sight that could pass for a gray/brown patina. It's not ideal but it's a whole lot better than a bright blue sight on a 110 year old rifle.
However, if you decide to go this route keep a close eye on the process. It doesn't take long for the blue to disappear and you have to watch so you don't "over-cook" it.