DIY battery cable supplier

Most auto parts stores would have what you need.
Or, welding supply stores.

This is the best place for what you need. Parts and custom cables are their specialty plus prices are reasonable.
http://www.genuinedealz.com/about/

+1 for genuinedealz

http://www.genuinedealz.com/custom-cables/custom-battery-cable-assembly

Delcity.net

Quickcable.com

Lugs are sized for SAE wire. Buy one gauge larger lugs for AWG cable

I ordered my new battery bank cables with ring terminal ends from AMAZON...

Roy Ken

I get materials and use their tools at West Marine Supply.

Thanks for the suggestions people!

and if your going to use cable larger than about 10ga (small wire number) look into a good hydraulic crimper, avaiable on ebay at reasonable prices. especially once you get to cable sizes from 4ga down to #0000.
crimp, cover with adhesive lined heat shrink. All of mine I used welding cable I cut to length, again cable cutters avaiable on amazon or ebay. Since welding cable is usually only available in black, I use red or black heat shrink as appropriate.

Made my own lugs using soft copper tubing, much more robust than any premade lugs that I have looked at.

Select soft copper tubing size that just fits over the wire.

Then crimp the tubing (I made an adapter from a piece of steel pipe sized just large enough for the tubing to slide in then used a vice to hold the steel pipe in place).

Then solder (hint, heat the copper pipe, not the wire, then test to see if hot enough to melt the solder by touching the solder to the edge of the copper pipe).

Then flatten the lug end and drill hole(s).

Trim lug length and connect.

Cost me not even a penny to make the ends for ALL of my battery connections and much heavier than what you can by. Tried this on my 250A stick welder when I needed to extend the leads. When to buy welder cable and lugs and realized those lugs were so skimpy that I could make my own and make them better and cheaper.