There seem to be about seven species of olm. There are existing names for many of them, but I'm not sure any of them can actually be used. I don't know if anyone is actually working on revising the genus. Many localities are protected or secret. Recent experiences with other troglodyte salamanders will likely lead to more captive success with these curious creatures.
Minnesota has plenty of herping, with about 51 confirmed species. The state is large - you could probably drive from southern MN, through Iowa and Missouri to Arkansas, in about the same time as driving corner to corner within the state. There is a three or four way split in distributions: the northeastern chunk, especially just south of Lake Superior, has most of the frogs and all but one of the salamanders. The tiny southeast corner has most of the snakes, all of the turtles, two of the three confirmed lizards, many of the frogs, and small populations of several salamanders. The western edge, especially a tiny spot in the extreme SW corner, has most of the leftovers, basically prairie species not found anywhere else in the state. The Twin Cities area is well-located for accessing most wild herps, and has at least two good zoos and a specialty reptile store, plus the state herpetological society. I was herping [with no luck] just north of Iowa yesterday and the day before, but I did find five species near here October 30 - November 1. As of today, there's snow on the ground, so Blanding's turtles and mudpuppies are likely the only things to be found until spring.
There are a number of zoos. The Twin Cities has the Minnesota Zoo and Como Zoo, both of which have interesting herp collections. Como Zoo is free, but parking can be a challenge. Reptile and Amphibian Discovery [RAD] Zoo in Owatonna has a large collection of herps and is privately owned and professionally run. There are also zoos in Rochester [Zollner Zoo], Mankato [a petting zoo in a public park I think], a possible new private zoo in Bemidji [the developers have a variety of herd stock], and an aquarium in Duluth. One of these days I may actually get some of my hundreds of photos online from native species and RAD, MN, and Como zoos.