Hi there, I think it must be because I have been speaking to a korcula travel agency (Mediterano tourist agency) about exactly this! And they gave me a price for a return day trip for with and without guide for when we are there (28 Aug / 12 September).
They are on facebook and are quick at replying. I think they quoted me around £80 for 2 adults one infant and guide. Can't get onto my facebook to check at the moment thought but I asked on there and they gave me the price.
Here is what they said:
We have option for excursion to Mostar with and without guide.
The cost for just transport (bus) from Korcula to Mostar would be 37 Euro per person (Under 4's free)
The cost for transport (bus) with guide would be 54 Euro per person.(Under 4's free)
Itinerary: Leaving the island early in the morning, driving across the Pelješac peninsula, short break in Neum at 9 AM, visiting Počitelj around 10.30 AM, arrival at Mostar at 11.30, leaving Mostar at 4 PM, arriving to Korčula around 7 PM
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