not sure on the soldering issue. making a chiller yourself is pretty easy. as pointed out, you may want to base your decision on the cost of diy versus purchase. though diy has its own rewards.
a couple of design considerations. I use a smaller chiller that was given to me as a pre-chiller in a bath of ice& water before the main chiller in the kettle. works very well. also consider your batch size. if you make a taller chiller to fit in a larger batch, part of it will be above the wort if you do a smaller batch occasionally. also, one problem with chillers is slinky distortion. you can easily prevent this if you wrap a copper wire around the coils, keeping them held together. or i've seen where a brewer soldered a copper bar vertically along the outside of the coil serving the same purpose. even if you buy your chiller, many of them don't have this important feature & you can add it yourself. also, the swan neck bend at the end of the tubes keeps them hooked over the kettle lip, keeping any possible leakage (at the fittings) out of your beer. you can do this easily using a cheap tube bender available where ever you buy your tubing & fittings.