If your keyword billabonghats has only 8000 monthly searches, and yet has high competition (I checked, it has very high competition).. I don't think it'd be worth it to try to get to the top of that particular ladder.. that's only 260 visits per day if every single person clicked on your link..
Use that as your main keyword and build pages related to it focusing on long tail keywords. A bit of hard work, time and link building you should hit the first page without having the keywords in the domain itself. Done it before myself. You could use words that are similar like billabongcaps for example?
In my mind i think keyword in domain name, it really helps in SEO.I can give you live example:-- Go to Google dot com and search "girls room" keyword.You'll see thegirlsroom.com is on no.1 postion.
The simple answer is that it isn't very easy.. but it can be made easier if you do the right research