DIY Heating Cables

Well, I'm doing a full tank teardown/rebuild this weekend and I still
haven't made up my mind over *how* to rebuild... help!

I'll be using laterite and sandblasting gravel for the substrate, but I
can't decide what to do in regard to substrate heating.  Originally, I was
planning to buy a Dupla cable and DIY the rest.  However, my wife and I just
acquired a 12-week-old black lab/chow mix, and an 8-week-old black
lab/german shepard mix, so you can probably guess what happened to my
disposable income.

I'm leaning towards a full DIY solution, as opposed to the cheaper
alternative of nothing.  I would love to hear from anyone who has blazed
this trail ahead of me.  Also, if anyone can explain why I now have fish,
two cats, *and* two dogs, I'd love to hear that too...

-Eric (in sunny, 75 degree Phoenix)
If common sense is so common, why don't more people use it?