mlgb

De Una Cafe (near my Candelaria Hotel) was connected with a travel agency. Perhaps they can help with more difficult parts,

De Una Colombia, http://deunacolombia.com/destinations

I had a few taxi (van) drivers quote me for private tours at around $200 per day, IIRC.

welltraveledbrit

Thanks so much mlgb, I'll check it out.

I've contacted the hotels/hostels in the local area and have got a couple of quotes back and it looks feasible. Apparently there's nothing in Tierradentro so you have to bring someone with a car or jeep or arrange someone to pick you up there in advance, It seems the vast majority of their visitors just take the 6am bus. We're hoping to make a couple of sightseeing stops on the way so I'd much prefer a car.

Everything is slowly coming together and we're very much looking forward to a rather serendipitous trip. Funnily the flights within Colombia will cost about the same as the international flight which includes a trip to NY. So much for our cheap deal!