Hate to differ with you, but is possible to use markers, life lines and interchangeables all at same time. Yes, the L.L. will be run through markers, but that is a good thing if (heaven forbid) you should have to rip back, markers will be there to guide you. I don't know about you, but I have enough markers of varying sizes and types I could use one on every row that has a L.L. and still have them left over. Besides once you place your 3rd or 4th L.L. you'll be removing the first and have all those markers to reuse.
If you're looking for a cheap alternative for markers, I purchased a package of jump rings used for jewelry for about $3 at JoAnn's and it has 100 of them in package. I can even loose one and not fill guilty, and not only that much thinner than the usual rubber or plastic ones sold on knitting aisle for $4 for 10.
