Hi Nishta,
A few items you may not be aware of to consider in your pursuit.
In my experience some smaller providers charges include a one off implementation cost, monthly support costs, on site training and monthly charges based on number of aircraft or number of crew. Interfacing will be additional costs and obviously any changes to meet business process, example, FTL Scheme and any additional Company/Crew agreements.
Are you looking for a cloud based application? Cloud provider costs may not be part of initial costs and will also be monthly, will it be a local provider, checking reliability of providers can be important and the response times of the providers to resolve bugs, implement new rules/requirements or response to a system failure are other important factors to consider, should a system failure occur for more than two hours what is the roll back process or how are the changes managed when the system is out.
Transfer of current data into new system, how will this work? Additionally, the cutover from one process to another and what happens if it fails? Is there a test bed provided or a live version only?
Hope this is of use,
cheers