Not so well known, and currently without a website, but check out Spithead Miniatures (they have a page on Facebook), who have an extensive range of ACW, South American and European Ironclads.
Phil is very prompt at sending price lists etc (ordering information is on the FB Page) - he’s a 1-man band for whom the modelling is a hobby who then makes the models available in limited production runs rather than a full scale business.
Photo of some paddle steamers taken from his page