I mean, I’v never seen a fly line manufacturing set up so I really don’t know. But how does a company Like cortland make one line that isn’t as good as another like a 333, or 444, or there fairplay line with out it costing them the same to make? and what really makes the difference?
I’m not an expert, but my guess would be that there is a different polymer coating, R&D… stuff that make is more supple, float higher, smoother\longer casting…whatever
And\or marketing to the people who have to have the newest\best out there…
Just my 2 cents
Sheeez Tim… stop thinking so much… 
LOL I think your right Gringo, good advice, I think I’ll take it…
There ya go! No way you could cast that fancy new flyrod with last year’s piece of junk, old techonolgy fly line.
Brad
What is the difference between a compact car and an SUV?
Different models use different materials at different amounts. There is also a certain amount of R/D that goes into each. Not every line has the exact same taper. This upfront cost is paid back in every line sold. More R/D higher cost per line. Cast a fairplay line, and then a 555 line and see which one shoots better, floats better, and lasts longer.
I tend to be a price point kind of guy. I want to pay half of retail for the most part and fly line is no exception. If the line retails for $70, I tend to pay $35 for it if I shop. I don’t care if it was top of the line last year vs top of the line this year. A good line two years ago is still a good fly line. Place like Bob Mariotts, Madison River or Sierra Trading post offer deals like this often. Why buy a mediocure fly line when you can get more for your money if you shop. Would never pay $30 for a $30 retail line when you can buy a $60 for the same price. Just the cheap bastid that I am of course talking. You pay retail, it you are out west and were too stupid to bring a back up reel with line and cut your only line in half or something else happened that made it unuseable. Then you pay retail, but not in Feb when there are so many deals going on:
http://www.bobmarriottsflyfishingstore.com/cat-Flylines-8576.aspx
http://www.mrfc.com/MadisonRiverShopping/SearchResult.aspx?CategoryID=4 If you like Cortland here is some 555 ($60 retail for $30) why buy Fairplay?
http://www.sierratradingpost.com/d/2249_Fly-Reels-and-Fly-Line-and-Reels.html
I tend to fish Rio or SA but that 555 for $30, I would give it a try.
New rod + new line = more money.
I sell $25 and $75 lines and this is what I know. There are innovations, materials, coatings and so on that cost money and we certainly must appreciate the folks that make new and better stuff for us to enjoy fishing. But . . . it’s true that the actual cost to manufacture these different lines isn’t much.
Is there a difference? Yes. Does the difference make a difference? Sometimes. The biggest difference I see, and I’ve mentioned this elsewhere, is that a stiffer line is more suitable to a faster rod . . . but a faster rod does not NEED a stiffer line.
That said, most casts are 40’ or less and the difference in spending a lot of money won’t be evident with the short casts for most people. Buy the way, I KNOW that our H&H fly lines are made from the best materials and coatings that money can buy. Does that mean that everyone likes it or that it is the best line to fish? No – it’s all a matter of what you like.
Ron