I recall buying a crimp terminal kit from HF and being pleasantly surprised at the quality. The kit I had gotten from Radioshack years ago wasn't fit for anything. Generally I buy Amp (Tyco?) from wherever, be it Home Depot or Walmart, when I need crimp terminals. Forget where I got my crimper from, it's generic but so far has handled what I have tossed at it.
The other question is what do you have for crimping tools? Larger lugs require a heavy duty crimper, I use a hydraulic one that does a nice job on larger cable lugs and a few other crimpers for different styles. It does no good to buy a bunch on terminals with no way to crimp them properly.
For larger lugs and wire this is the best place I have found, always top quality pure US made wire and high quality lugs. I buy my 1/0 battery cable from here, great fine strand stuff.
Arolax Cable Stripping Tool – With Adjustable Cutting Depth – For Circumferential, Longitudinal, and Window stripping – 3/16" to 1" Diameter. - - Amazon.com
There are many other tools for different connectors like Delphi and Deutsch, for automotive use use only tinned terminals, ground strap braid cable and lugs not plain copper.
There are also solder lugs with the slit in the front, these are best crimped then soldered.
Heat shrink crimp terminals are excellent for automotive use and are much better than standard nylon non shrink types.
Hope this gives you and the other members some ideas. There are many other companies that sell supplies and more tools are available, this post is not intended to include the only ones or the best of them
Up to about 14 Guage I always get only Stainless terminals with higher physical strength and never aluminum. Aluminum with high current (heat) expands and contracts and the connections can loosen over time causing voltage drops and even more heat. When crimping never crimp so hard to crush the wires. This will cause voltage drops and also failure points. A good set of crimping pliers without fancy force multiplying leverage are best for crimping (Keeps you from over crimping) Bought a pair from Grainger 30 years ago i still use today like these. Klein-Tools-1005