When buying any modern electrical consumer item, it really is advisable to do your homework first. Whether it be a 3D tv, a mobile phone or a laptop, it makes sense to do a little research into the type of device you are after, and then the products available.
One way to do this research, is by visiting electronic review websites on the internet. Here, devices are tested and points of view given covering both their positive and negative aspects. These can be a good base to start at, although it is worth pointing out, that some of these review websites have a vested interest in the products that they are writing about.
With this base knowledge, it would then be a good idea to source some customer reviews about the products that you are interested in. These opinions have a rougher feel than the professional review websites, but they do come from real people, just like you. The best reviews are from people that have owned a product for a little while, as they can write about their experiences over time. A "just out of the box" review really is of little help!
With these two steps complete, you should have a better idea about which device it is that you want to buy. Now, it's time to find who sells it for the most competitive price! Again, the internet is great for this, as even the major high street retailers have web stores. Price comparison sites are a good place to start, as they have already collated the information and prices.
Hopefully, after following these steps, you will be able to identify the product that is best for you, and also be able to buy it at the keenest price. Always remember to return the favour to the consumer community, and leave a review about what you have bought!