Although I am insufficiently knowledgeable to be the best judge of absolute authenticity, I have had considerable success in dealing with Sanjay Suri in India (Ujna Universal, a.k.a. "Replicaters" ) -
http://www.replicaters.com/victorian.html(Scroll down most of the way .....)
Current prices (made to measure and
including delivery anywhere in the world by air express) are listed as follows:
Tunic - US$173; UK£92
Trousers - US$92; UK£50
They are actually willing to make just about
anything, if one supplies pictures and/or other information they can work from although, in such cases, one must be very careful to ensure any possible confusion over details is fully clarified .....
For something as "standard" as a Zulu War-era uniform, however, all you'd really need to supply is your measurements. Here is an acquaintance of mine in his 24th uniform, obtained from Ujna upon my referring him to them -