Sightseeing uber from Graz Port to Mt Srd summit

[Kiwitravelbug]

We will be on a cruise stopping in Dubrovnik in early October. Rather than booking a shore excursion, I would prefer to take a scenic taxi ride from Graz Port to the summit cable car station on Mt Srd, via the Franjo Tudman Bridge, and the Ombla River Spring (with photo stops).  We would like to be dropped at the summit and catch the cable car down to the Old Town base station.
Approximately what price should we (2 passengers) expect to pay for this scenic drive? Will we have to haggle for a taxi, or can I arrange this with Uber or Bolt?

Will it be possible to get one-way descending cable car tickets at the summit if we didn't go up on the cable car?  On the cable car website there are prices for one way tickets, but it only refers to tickets being sold at the bottom ticket office.

Thanks for any advice you can share.