I'd recommend using
Google AdWords. You need to make sure you can convert the visitors to customers though, or it could be a very expensive exercice with very little (if any) return! Get a few people to review your site and listen to their feedback, it will help you a lot.
Once you've ran AdWords for some time, look at which keywords are providing the most traffic/ sales and start to work on their natural search engine positions. In the long run, this will save you a lot of money.
There are millions of ways to promote your site, many of which have been discussed before, I'd recommend using the
search for this one.