The most readily available "affordable" repeaters (and not microbrands) are Citizen and Invicta -- there are some really cool Citizen models. There are some guys who have taken old Angelus pocket watches and done one-offs. Paige comes to mind on that as well as TNT/Extreme Watches. Check out the homage forums for more guys who do that. Xeric supposedly has one in the works as well.
If you really want to go down a rabbit hole, there's a guy in China named Qin Gan who is a tinkerer and made some really interesting pieces -- enamel dials, retrograde dials, repeaters, alarms, etc. If it was on an old railroad pocket watch movement, he would play with it to make it unique. I've seen a few pieces of his for sale over the years. It helps if you have a Chinese translator app and someone you can have double check it. I don't think I've ever seen anything on his stuff in English.