Effort estimation to integrate SAP & Non-SAP systems

Hi Experts,

I need to have an idea on the effort estimation to integrate SAP and Non-SAP system. Ball park estimate could be enough for me.

I do understand that this can't be answered without having proper information. So, let me please ask the following questions.

i) What are the parameters should be considered to measure the complexity of one interface?

ii) If we categorize the complexity into simple, average and complex then what should be the ball park effort-estimation on each category?

iii) Assumption1 can be made that developers are well trained.

iv) Assumption2: Interfaces are identified.

Any kind of experience sharing is most welcome.

Regards,

Soumendu