Our experience going Southbound as most reported here seem to be Northbound. Definitely possible independently and could have been done pretty cheaply if necessary.
9am arrived at Khojeli Konye Urgench border.
11.45am clear border and get a driver to take us around Konye Urgench sites and drive us to Dashoguz. Price $10 for 2 ppl (could probably have negotiated down more but we had no manat yet and there was nowhere at this border to get manat)
2pm set off for Dashoguz
3.30pm driver takes us to change money in Dashoguz.
3.45pm Dashoguz train station. Aim was to buy ticket for that night from Icoguz to Ashgabat so we didnt need to stay overnight at crater. Unfortunately chaos at station and no tickets to Ashgabat were being sold to anyone. We decided to still head to Darvaza and will just figure it out there.
4.15pm new driver takes us to Darvaza directly for 150 manat per person. Normal car managed just fine to get whole way to crater. No need for 4x4.
7.30pm arrive at crater. Went to yurt camp at back right as only one with multiple yurts. 1 yurt available luckily. Price $15 pp inc 2 course dinner, water and breakfast. Could have paid $10pp for just yurt and no food or shower use! But we hadnt eaten since breakfast.
Guys at camp said they will drive us to teahouse on main road next day. Initially asking $10 but agreed $5. There were also 2 younger local guys on motorbikes seeing if anyone wanted to go to Icoguz train station at 1am or main road next day.
7.25am head to main road. Back up plan was to get a bus to Ashgabat. We were told it would be there about 10am. We saw buses heading north while driving to both Dashoguz (would have been at Darvaza c. 10am) and Konye Urgench (probably 11am).
Instead we decided to hitchhike so we wouldnt have to hang around.
7.40am after c. 15 mins the 5th vehicle to pass us Southbound stopped. It was an old lorry with space in cab. No expectation of payment and he stopped at water crater to show us. Really nixe guy
It was slow but all the cars we saw were full or private tourist jeeps.
12.30 get dropped off at shared taxi station North of Ashgabat. Paid driver 100 manat (so 50 each) as thank you. He seemed very happy.
12.45 got bus from stop outside station. Both that go from there terminal at Teke Bazaar. Route 47 and 53.
Walked to some hotels.
Not Plan A but a pretty good Plan B