Go to this site to research a reputable mechanic in your area (by zip code). Its best to have someone do this who does it all the time. The kit probably includes a pulley or tensioner - which it may or may not need - a good mechanic who sees these almost every day will know when he takes it apart. In addition to the timing belt job, you should consider replacing the water pump at the same time, since 90% of the labor for that job will be included in the timing belt job. Yes, this is one time when it may make sense to replace a part before it fails. Discuss that with your mechanic also. Figure 300-400 depending on where you are + water pump cost & new coolant (I use the red Toyota coolant). Ask about belt warranty and the brand belt he prefers and why. Also a good time at 8 years old to check condition of all hoses.
The cost will almost certainly be cheaper at an independent - although your local Toyota dealer may have timing belt specials or internet coupons for as much as $100 off the repair cost (which might bring it down to the cost of an independent).