Mod suits are kind of making a comeback, thanks to some 60s nostalgia and some hit TV shows like Mad Men.
Mod fashion was somewhat a reaction toward the more conservative 1950s. Clothing became more colorful and stylish. Men's wear got more stylish and the look and feel definitely changed. Designers started featuring things like more slimmer fitting pants and tailoring custom fit to the wearer. English and more specifically, London, was the center of fashion trends, rather than French or Italian designers. Think of the Beatles.
While hippies in the 60s were showing their psychedelic side with wild colors, black was still the norm within menswear. Most of the changes were in slimming: the lapels were narrowed and pockets were shrunk along with more fitted pants. The jacket bottom has a more pronounced curve from the buttons.
Brand new versions are hard to find in stores. While the older trends are making a comeback, most current fashion houses don't really cut their cloth that way. Your best bet may be something like eBay.