I am planning to travel from Tbilisi to Baku via the Red Bridge border crossing.
Could you advise me what time buses and marshrutkas leave from Tbilisi's railway station bound for the Red Bridge border crossing?
You have to go to the main station and ask around, the prices are very different as there are no actual companies driving. The drivers are individuals who drive families and tourist to the borders.
I will ask my friends in tbilisi to find out the estimate price but meanwhile I did my research and found this gem website.