After reading this article (http://www.silverstripe.org/migrating-a-site-to-silverstripe/show/21102) on how to migrate a current site into silverstripe, got me wondering - is it really so darn easy, eg. If I purchased a theme from themeforest.net. Would it be cheaper and really that straightforward, than having a company building me a theme directly (in silverstripe).

Of course it dependes on the modules in the bg. and what the functions do. But i general is it easy to just implement a fully functional and structured html site into silverstripe, like the ones selled on themeforest? There will be some extra coding of course.
Im not a web designer so sorry for any dumb questions

Im open for any good suggestions, what is the best way to go forward. I have a feeling that the companies will charge a lot for a theme.

Also, would be appreciated a lot if anyone would have good links to professional ui/ux agencies making silverstripe themes, so that I could look at some. So far I've found:

http://dna.co.nz/

Also this is what inspires me:
http://www.behance.net/Oberhaeuser
http://www.behance.net/dannpetty
http://www.behance.net/cfaydi
http://www.behance.net/ghoshal
http://www.behance.net/arocha
http://www.behance.net/bady