Beopju is the traditional wine of Gyeongju. It has been made here for hundreds of years at the Gyodong Beopju. The Gyodong beopju is the finest, but it is very expensive: 30,000 or 33,000 won per bottle. However, you can buy cheaper beopju from other producers for as little as 6,900 won per bottle in the local supermarkets. The cheaper stuff has a similar taste, but it is a bit rougher. The Gyeodong beopju is superior: you can definitely taste the difference, but I am not sure that it warrants such a big price difference. Anyway, when you visit Gyodong Beopju, they will let you try a glass for free! Oh, and in case you wondered, it is made from glutinous rice.
Almost every other shop in Gyeongju seems to be selling boxes of Gyeonju ppang (ppang is the Korean for bread). Gyeongju ppang is actually a very sweet bread roll stuffed with red bean taste: too sweet for my taste. It is very expensive bread too: the cheapest box costing 10,000 won.
Around Gyeongju, you would find many bakeries selling Gyeongju bread. Many are endorsed with the smiling face. On first sight, it seems similar to the Japanese an-pan (red bean paste bread). The crust of the Gyeongju bread is made with rice or barley flour and very soft and thin with a generous dollop of red bean paste.
Not as sweet as the Japanese counterpart, but still sweet nonetheless, it is the perfect accompaniament to a hot cup of barley / green tea. You can also get it at the food courts in Incheon airport but slightly more pricey. Not good for keeping for long periods as it is a fresh produce (but I polished off 5 over a cup of tea).
There's one on the right of the exit at the Tumuli Park in Central Gyeongju, another across the road from the Bulguksa temple carpark. Some others in Gyeongju downtown.
What to pay: Can't remember (i think about US$12 for about 25?)