It is clear that spice was costly and that the Guild Navigators used large quantities of it:
Herbert notes in Children of Dune that the geriatric properties of melange had been "first noted by Yanshuph Ashkoko, royal chemist in reign of Shakkad the Wise." By the events of Dune, the spice is used all over the universe and is a sign of wealth; Duke Leto Atreides notes that of every valuable commodity known to mankind, "all fades before melange. A handful of spice will buy a home on Tupile." Due to the rarity and value of melange and its necessity as a catalyst for interstellar travel¹...
The spice being so costly, and by being such huge consumers of the spice can we gauge what the Guild charged for space transportation in return?
Can we say how costly was Guild based space travel?
Or is there an example of what space travel cost in the books?
The cost to someone in terms of spice or solari for transporting a described good or object. Obviously an exact number like an airfare is impossible. I'm looking for some indication from the novels, or even the movies.