Every summer in late August, JARL Ham Fair is held at Tokyo Big Site in Japan.
It is usually a two day event and is the largest ham fair in Asia.
New and used ham gears can be bought at bargain prices.
For more information please see http://www.jarl.or.jp -> English.
Round trip air ticket between Seoul and Tokyo costs about $300-400US.
The cheapest way to go to Tokyo from Busan and back is to use Air Busan(www.airbusan.com) which costs about $150-$200 round trip. Air Busan is a low cost airline company started a few years ago. Use possibly Haneda airport rather than Narita airport in Tokyo because Haneda airport is more convenient to access Tokyo downtown area by subway.