This happened a year or two ago but the memory just descended on me in a flash of blinding deja vu that was so powerful it was frightening. If you're a consultant and a customer calls you with a problem, there's only one answer:
I remember this vividly. I was in the final stages of a project – I had just assembled the staging server and I was looking forward to the end of the night and sleep, blessed sleep. I heard from the customer who was clearly panicked. His vendor was holding him up on a data migration issue and was charging an arm and a leg and then three more body parts for something simple – $25K for migrating 60 users from staging to production. I'm not going to say the vendor since they're long gone. I would point out that the charge for the migration was more than my whole software development bill to that point.
So my answer to the question of could I handle the data migration – Yes. When I said it, I didn't know anything about the data I was migrating. I didn't have a schema, properties, etc. What I did know was that $25K for doing data migration was absurd and, as a consultant, I'm there to help the client. Always remember that – you're there to help the client. So even though I didn't want more work, I'll still do it and, ultimately, the client will remember who helped them out in a point of crisis.
Bottom line – if you're a consultant, the answer is yes.