In the world of toys, a toy soldier is perhaps the biggest icon. Indeed, it's believed that many of the earliest toys in the world were representations of military figures.
Military personnel from all throughout history have been immortalised in the form, including medieval knights, cowboys, pirates and traditional army soldiers.
Figures range from those specifically designed to be played with (the Action Man range is a good example) to those that are actually considered genuine authentic and accurate figurines. Some of the latter come supplied with genuine, hand-stitched uniforms to add extra authenticity.
In the sense of Toy Soldier costumes, though, the design is genuinely influenced from either the Victorian or Georgian era, with the crimson design of the time a key part of the design. This isn't always the case, of course - some toy soldier costumes are based around more modern camouflage - but generally speaking that style is the most common.
As with all fancy dress costumes, it's a good idea to hunt around and see if the right costume can be found for a lower budget. Second hand purchases are often a good idea in this sense, as they represent the chance to get a (usually) only-worn-once costume for less than half of the RRP.