ISMS Budget

Answer:

There are a significant number of variables to be considered when estimating an implementation cost, but you already have figured out some important issues. Broadly speaking, I can suggest you these main topics to consider:
- Training and literature
- External assistance
- Technologies to be updated / implemented
- Employee's effort and time
- The certification process

Regarding ISMS maintenance costs, the above mentioned costs also have to be considered, but at different levels, and you have to add the surveillance audit costs for certification maintenance.

These articles can provide you more information:
- How much does ISO 27001 implementation cost? https://advisera.com/27001academy/blog/2011/02/08/how-much-does-iso-27001-implementation-cost/
- 5 ways to avoid overhead with ISO 27001 (and keep the costs down) https://advisera.com/27001academy/blog/2012/06/19/5-ways-to-avoid-overhead-with-iso-27001-and-keep-the-costs-down/
- How to Budget an ISO 27001 Implementation Project https://info.advisera.com/27001academy/free-download/how-to-budget-an-iso-27001-implementation-project