Dealer price is definitely high, BUT BUT BUT: Not all "timing belt" services are created equal.
On many cars (I don't know if this applies to yours or not), a full timing belt replacement service includes a number of extra parts, including tensioners, all the other belts, and most importantly, the water pump gets replaced, too. If you don't get the water pump replaced at this time, it's more likely to fail before the next timing belt change, and cost an arm and a leg to get to, since you basically have to do a timing belt service just to get to the water pump. This happened to me when I was young and wanted to save a buck. 20,000 miles later, the water pump failed, and it cost me way more to replace than if I had had it done when they already had the engine torn apart for the timing belt.
Understand also that timing belt services can be hugely intensive on some cars and easy on others. So if the local shop isn't familiar with your car, they could end up charging more than their quote once they see what they are dealing with. My advice is to find an independent mechanic who specializes in Hyundais. He'll probably charge somewhere in between the dealer and the other guy.