Title text:
Detectives say the key to tracking down the source of the kites was a large wall map covered in thumbtacks and string. 'It's the first time that method has ever actually worked,' said a spokesperson.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3121/
Doing some quick math here:
Circumference of the Earth is about 24k mi = 44M yds.
The cheapest fishing line I could find online (from Amazon) (I didn't search very hard though) was $10 for 440 yds of line. To circle the Earth, you'd need 44M / 440 = 100k spools = $1M for the fishing line.
Let's assume every spool needs about 1 kite. That's 100k kites. You can find kites online for like $5 each, but the cheapest way to get a kite is probably to bulk order wooden sticks and plastic film and make them yourself. Let's do the math on that.
Assume each kite requires a generous 5 ft^2 of film, and 10 ft of sticks. I found some bulk plastic film rolls online (from McMaster Carr) for about $0.02 per ft^2, and some wooden marshmellow sticks (on Amazon) for about $0.10 per foot. That makes $0.02*5 + $0.10*10 = $1.10 per kite. That totals $1.10 * 100k = $110k.
So using these estimates, this kite ring costs around $1.11M.
No clue if it would actually work though.
Edit: corrected a math error
Anyone want to make it? I'll donate $20 to the cause