Great, those Magento template sites providing cheap or even free templates! However, before you start you should be aware of these possible issues:

1. Most, if not all, of the cheap or free templates look a lot like default Magento installations. If that is not what you’re looking for, it will probably take a sizeable chunk of your time to modify the downloaded template to your liking. You should really determine what your time is worth: contacting a Magento implementation partner might be a good idea if you want to keep your focus on business instead of development…
2. The good templates are downloaded a lot, which means that in time, there will be a sizeable number of other shops which will have almost exactly the same look as you have.
3. Competitors or new market entrants can find out quickly how your front-end came to be – and replicate the steps to your success.
4. A front-end is only one part of your shop. Your shop management, back-end integrations like integrations with payment service providers, logistics etc. are the backbone of your processes and should receive ample attention. The back-end processes should be carefully thought out and a good design for those is one of the main competitive advantages you can get.

There are many excellent and cheap Magento templates but using one should be a carefully considered decision. In short, downloading a template is only a possible shortcut for getting the presentational side of your shop up.