It's difficuit to measure the value of a present by the cost of it. I personnally think that a 6 year old kid (K3 ?) might need something more practical like story books and stationery. You can check what cartoon characters he/she likes & buy something like a Winnie the Pooh story book or Hello Kitty stationery pack/set. These things many cost from under $50 up to $200+...but I don't think the cost matters too much.
My son just had his 5 years old birthday at McDonald's. He received one junior scrabble, one junior monopoly, a flik flak watch, 遙控車, some T-shirts and many story & educational books. Luckily, no big toys. I think the best is to buy something that is educational and useful instead of toys. Price range should be around $150 - $200.