I'm using Fodera strings for this purpose, but here is what Thomann is proposing : https://m.thomann.de/gb/search.html?categoryKeys=GISAEB5S&maxPrice=46&q=5+string+high+c+set&s=price
But you can also buy a regular 4 strings set and add the extra high C needed if the brand sales single strings. D'Addario, Kalium, Newtone and Elixir are the easiest to deal with for this and you can even create your own set with the gauges you want by these brands.