One of the earliest upgrades I made to my brewing setup, in fact right after my first brew, was an immersion chiller. I bought about the cheapest one i could find on Amazon, thinking what the hell its just a coil of copper how could they mess it up. Well, the hardware the included was tubing that was just a bit too big (it slid right over the copper - not snug) and hose clamps.
After fiddling around with the setup for three brews i got sick of having to cut down the chewed up hose, trying to tighten the hose clamps correctly, and wrecking the ends of my copper, sometimes to no avail, still having small leaks.
So, I went to ace hardware and bought 50$ worth of brass fittings and copper, yeah almost as much as the chiller itself cost. It would have cost less if my copper ends weren't so gnarled but the needed to be cut down and then extended out.
anyways what i have now has two hose fitting on each end and is 100% water tight, if anyone is curious to the process/parts I can get the names but I cant remember off the top of my head