Here's what I've learned about DCC wiring, and wiring for layouts in general.
Feeders. For reliable, trouble-free operation, each piece of rail should have its own feeder. This means that you NEVER rely on rail joiners to carry current on your layout. They are only for track alignment.
So, if you're using ME flex, you should plan on one feeder on each rail near the middle of each piece of flex, whether that piece is 1" long or 3' long.
Does that mean you're going to have a lot of feeders? Yup.
Feeders should only be about 6" long, and I use 22 ga. solid copper wire.
If you're worried about appearance, solder the feeders to the bottoms of the rails (the rail "foot").
If you're not worried about appearance, bend the feeders at a nearly 90deg. angle and solder them to the sides of the outsides of the rails.
Use a 30 Watt iron with a wedge tip that's clean and tinned for each solder joint. Always use a non-acid flux to aid your soldering (IMPORTANT!).
Touch your iron to both rail and feeder at the same time, and feed a little solder to the joint. Don't try and solder your feeders by placing the iron on top of the rail, or you will melt ties.
If you're melting ties, cut the spacers away three ties on either side of where you're going to be soldering your feeders to the rails, and slide them away from the planned feeder position. After the joint has cooled, slide the ties back in place. Voila! No melted ties.
On a small layout, you'll easily get by with 14 or 16 ga power busses for DCC. These should be high quality stranded copper wire.
I use this color code: Feeders...RED goes to the "outside" rail, BLACK goes to the "inside" rail, GREEN goes to the turnout frog. Power Busses...RED goes to the "outside" rail, Black goes to the "inside" rail. You can use whatever color code you like, but red/black or red/white is what most layout builders use. Write your code down, and glue a copy of it to the bottom of your layout somewhere.
The cheapest and most secure way to connect feeders to power busses is to simply solder them together.
The quickest way (and not bad electrically) is to use 3M Scotchlok Insulation Displacement Connectors instead of solder. You can find them on eBay for less than a dime each.
It has been conjectured that because the metal part of the 3M IDC is aluminum and feeders/power busses are copper that some corrosion will inevitably take place. I have nearly a thousand connections using IDC's and I have never had a problem. However, I live in a desert climate. If you are worried about dissimilar metal oxidation happening, then use an oxidation inhibitor on each IDC connection such as Noalox, which you can buy at Lowe's or The Home Depot.
You do not want to get "cheap" wire. You want low oxygen, high purity wire. For your little layout, the price difference is not going to be worth it. Learn good wiring practices early, and use them in all your layout projects.
Lowe's and The Home Depot's wire prices are high. I buy mine at my local electrical supply house, where I can "talk shop" with somebody who knows what they're doing. Another place that may have what you're looking for at a fairly good price would be a car stereo install shop. I have one who sells me wire by the foot at a much better price than Lowe's or THD, and they usually have a fairly good assortment of connectors too...although local prices are always much higher than getting connectors through eBay.
If you decide to create more than one power district, I identify mine using colored electrical tape on the power busses and by sticking a piece very close to my subroadbed (under the benchwork) where the two feeder come through.
I also secure my feeders with gap-filling CA and Accelerator on the underside where they come through the subroadbed so they won't pull off the bottoms of my rails above. It acts as a "strain relief".
I also string a straight DC power supply line alongside my power busses, which I use to power my Tortoise switch machines and my Digitrax UP5 Loconet panels. I have a Radio Shack 12V 1.5A power supply wired into this circuit with a 1.5A quick-acting fuse. I use 14 ga lo-ox speaker Zip-wire for this. This little power supply powers over 30 Tortoises as well as 9 Digitrax UP5 panels without a hiccup.
Just for your interest, here's the wiring setup on one of the yard modules on my modular layout. Its specs are different than what I've recommended for you in these ways. I use 12 ga. Red/Black Speaker zip wire for my main power busses, and I run 14 ga stranded wire for my sub-busses, which all of my 22 ga. solid core feeders are connected to. I use 3M 905 Red Scotchlok IDC's for my feeder/sub-buss connections and 3M 902 Brown Scotchlok IDC's for my sub-buss to main power buss connections. My Tortoises have their own circuits using 22 ga wire blue/yellow throughout, with a solid green feeder going from each Tortoise to power the turnout frogs.
I'm sure you'll have other recommendations on this thread. My way works flawlessly for me, and maybe you'll see something that will assist you in my reply.
