Koper - tours for 2 to the Caves

Hi all

We are off to croatia/Sloviena/Albania (and italy!) with Thomsons next month. We usually DIY in ports, bar we did a fantastic 2 day Alla tours in St Petersburg (just 2 of us, and it was on a small bus for 16, they filled the bus) and we did the P&O Rome tour as it was too far to want to risk the train there.

So in Koper, there do seem to be private tour companies, but they all want minimum of 6 people to book it (or of course just 2 of us and pay for the missing people)

A tour of the caves at Postojna seems the best tour = Thomsons is £50 each

So is there any options for just 2 people bar this? The local tour companies have booths at the port, do they fill up busses on the day for tours? Or does it not work like that.

Also happy to get a taxi/bus there and pay entrance if that is practical (we did that to some of the galciers at Olden)