Gursikh133, The main purpose of this forum is to ask questions related to the videos. I will not be touching "cost" related questions.
Few things you need to do:
*) Define the purpose of your upgrade
*) Decide whether to upgrade or whether to re-implement. You might want to re-implement if you wish to recreated organization structures in the systems (like ledgers, legal entites, operating units, security profiles etc.) to take advantage of R12 features.
*) If you decide to re-implement then define the data migration strategy for AR customers, AR Open Trasnactions and Receipts, GL Journals, Historical Balances etc.
*) Figure out the functional impact on existing business procedures.
*) Figure out the impact on current customizations/interfaces. What percentage of work has to be redone. Study the ER diagrams.
*) Find out from Oracle the hardware requirements for R12 server. R12 is more demanding than 11i in terms of resources.