There are generally 2 types kiosk: informational and transactional. And kiosk comes with 2 parts: Hardware and Software, the quantity and level of customization will influence the cost a lot, especially software.

Will you want 1 kiosk or 500?  Price per kiosk will drop drastically as quantity goes up, as the software development work is spread across a greater number of kiosks. Spread $10,000 in development costs across 500 kiosks and the cost is only $200 in development per kiosk.

The kiosk hardware cost will be influenced by configuration:

Is it tablet-based information terminal?
Is it a bill-pay stations?

Does it take payment in cash or card?

Does it give changes in cash?

Is it for Indoor or Outdoor?

…

When you start looking at costs, think of it as a 3 factor project:
1. Kiosk Hardware
2. Kiosk Software

3. Quantity