I'm planing to take a bus between these two cities...i know that the price is around 100$ one way...
Does anyone know what's the route,does it goes through Paraguay or it's stay in Brazil the whole time? That's important to me because i'm traveling with two Canadians and they need visa for Paraguay.
Generally, US and Australians are due to pay an extra fee any custom border they cross in South America.
In fact by flight is often avoided and sometimes by bus ... it depends.
About the visa, latin america is not so straight as you think and especially the paraguay, if you pass through foz de iguazu(Brasil) or puerto iguazu(Argentina), often they do not check any visa or other stuff, in other way they do it on the go.
A Canadian (or American or Australian) can't cross into Argentina - including Puerto Iguazu - without paying the Reciprocity Fee.
The bus usually goes via Campo Grande. Rarely do buses use other routes including the one through Paraguay. There are even few direct routes into Paraguay from Cuiaba.
No need to worry about that bus trip, but do check if you want to cross borders after that trip like mentioned above.