I'm not exactly sure how the lotteries work. Participants buy tickets from different series which seem to sponsors specific projects, and each ticket has a serial number on the front. I believe they cost 500 won (about 50 cents) each, with the grand prize apparently being 100,000,000 won (about $100,000). It appears that at over 600,000 tickets were issued for any given series based on the numbers below, but I'm unsure if the grand prize was given for the entire series or for each individual ticket number.
The Olympic Lottery had about 300 tickets. I found research that shows up to number 299. Each ticket has a separate image on the front, and as you'll see below these range from Korean and other nation's cultures, to Olympic sports, to even the actual venues themselves (meaning the last series tickets were probably sold during or after the Olympic games were held.
I've seen these a few times now. I think the first time I noticed them was at the Seoul Olympic Museum last year, which had a display of most, if not all, tickets. While browsing flea markets, a few vendors have had them on their tables, but they always ask an extremely high amount for them, and given their condition and high print run (600,000+ printed each?) I'm not willing to pay that much.
Finally one buyer at a flea market sold me a bundle of about 150 for around $10, or less than 10 cents per ticket. They aren't all different though; I now have 81 unique tickets. I'd like to finish the set, and my research earlier this week found a website where someone was selling almost all of the tickets individually, for about 15 cents a piece (the first few numbers were more expensive). I'm not sure how I could possibly get registered and purchase the missing tickets from that site, and have them shipped to Japan. But it's worth pursuing in the near future, even though at 15 cents or more each it'll require another $30-40 at least!
And while I'm at it, if I lived in Korea and had the time, I'd probably look into some of the other series that have been issued. As I mentioned, I also saw housing lottery tickets, and some tickets referencing the World Cup.
Here are the tickets I bought. They are 3" high by 4-3/4" wide.