Go to the NAPA auto parts Website and search for "Balkamp". You'll come up with a bunch of tubes. Just sort through them till you hit the 1/8 inch O.D. It's clear, flexible (not too flexible) and works great on Renzetti tube vises. Two problems, are it's more expensive than spaghetti line, has black writting on it, and worst of all, you can't buy it online, you have to go to the store (call first, they may have to order it). Also search for one of my posts on tube material if you do want the black spaghetti line. I put up the NAPA auto parts sku, company name and parts number on that post.
Good luck. And let me know when you're ready for rods if you like old sages (7136, 9140-4). I may have some I'm looking to pass on and we may be able to agree on a price