Define expensive. If you are not familiar with electric circuits you may want to do some research, first. There isn't anyway for us to tell you what may be involved in doing this in your house from the breaker panel out to your grow area. The price of the wire has gone up a lot, like 200 or 300% in the last 5 or six years.
Labor for having it done will still, in my opinion, be the most expensive part. The exception to that would be, "I don't have any tools so I have to buy everything I need to do this". Drills, etc.
Before I put in my grow room I bought a book that I would recommend, Wiring Simplified. I have one of the rare copies of the 40th Edition and its based on the 2002 National Electrical Code, so you might not be able to get my outdated book. Code's haven't changed much in the last few years, and the book has more information than you should ever need. It also has information you do need, like Chapter 9, Outlet and Switch boxes. I bought mine for $5.00. The full retail in $10.95. Good investment. VV