Have you searched under the title "hunting pinks/pinque"? A friend of mine has a beautiful red tailcoat that he purchased from Huntsman London, it is a great variation at formal affairs. He had a lesser expensive one he purchased before the good one from Huntsman. I am not sure where he got that one.

Another option would be Ravistailor.com a Thailand custom tailor(don't laugh). I have had one blazer cut by them several years ago and it was not Saville Row but not bad. Their quality has improved since then. The same friend as I mentioned above has had several "very custom" items made by them(Think Duke of Windsor). They have a Spencer Jacket in their formal section that I have considered having made in red, if they don't have the fabric you could send it to them. My friend sent them several yards of tartan and had a dinner suit made in tartan. The prices are not give away but incredibly inexpensive for custom. A red spencer would probably cost between $200 and $400.

My suggestions, good luck.