I've bought sleeving from China via Ebay to make my lines, and although it takes a bit longer, a number of China purchases I've make via Ebay over the last couple months have all arrived as described and within the time they quote
http://www.ebay.com/itm/2-5M-Kite-lines ... 27d043344f
That item is for 10 meters (5 meters of each color) for $8.75 with free shipping to USA.
I know that beats the sleeving kits you referred to, but you need to be patient for delivery.
As best I can tell, only two colors available: blue and orange.
Hey, I bet if you ask for 50 m they'll give you a better price per meter. Ask for other colors, they might have? If you do, would like to know.
If you think of buying their 300 lb test high tenacity spectra for a kitesurfing kite lines, don't. I bought some to see what it looked like. Too thin. They have 400lb and 500lb test but I've not bought any yet. Prices look good.
I have no affiliation with them. Buy at your own risk - I have friends who absolutely won't buy anything Ebay from China, but I've had good luck. Ebay is on your side if there is a dispute and you not trying to pull a fast one.