Why are v drums so expensive?
The main reason electronic drums are so expensive is that they cost a lot to make. They involve a lot of different components, and to get a reliably good sound and feel, the parts are more expensive. On top of this, the research costs and development of the products probably plays some part in the price, too.
Is it OK to learn drums on an electronic kit?
Plus, you'd have a real set of drums available. I tend to practice with just my electric kit these days, but that's mostly because of space concerns. There's definitely nothing wrong with learning on an electric kit, just make sure to practice on some lower rebound surfaces periodically (like a pillow or something).