The use of a mod chip is one of the two main options when looking to unlock a wii. When going with the mod chip option you can either by a console with a chip already installed (pre modded) or buy a wii chip after you have purchased the console
Wii mod chips can be quite expensive, costing up to $100. Once you have purchased the chip you need to make the decision to install it your self, or pay someone else to do the instal for your. Paying someone to install the chip will take time and add even more cost to the exercise, learn.
The installation of a wii mod chip requires a fair amount of technical ability. The wii chip usually neeeds to be soldered to the console's DVD drive motherboard. This can be very difficult if you are not sure what you are doing, and could easy result in damage to the console. Even when you pay someonone to do this job you could easily end up with a poor install that will lead to problems in the near future.
Many of the newer design wii chips are much easier to install as they simply plug into the motherboard of the console, however you still have to physically alter the console itself, meaning that you will void your warranty on your wii.
The other option for unlocking your wii is to softmod or software unlock it. The wii softmod option is much quicker, cheaper, and easier and requires no physical alterations to the console. There are a few really good softmod programs that will have your wii unlocked in a very short time frame.