that depends on so many factors

1. are both DB compatible ?
2. are both DB directly compatible (do you need an intermediate level)?
3. Price of new S/W & H/W
4. Professional expenses.

debasisdas, thanks for your answer.

Let's just say that points number 1, 2, and 3 could be eliminated. How much do you gonna rate the Professionals?

Is there any standards, or we could say, average price per rows/ columns of data..?

I don't think size of database is a big factor. What matters most is how complicated the design is and how easily the existing features can be implemented / migrated in the new version/database. You need to remember all the db software allows to implement all the possible architecture but the way that is implemented is different. And this is the most difficult part. Migrating the data in tables is probably the easiest part. The toughest part is the implementation of business logic.

I still don't have a clue...
yes yes yes... couldn't agree with you more on above posts.

But, how could we estimate the required cost to migrate the data from one db to another... i need a formula... a standard cost... or man-hours rate that i could refer to...