14 gauge wire is good unless you go an extremely long distance, more than 25 ft.
Total Resistance
Wire Gauge Resistance /Ft. 5ft 10ft 25ft 50ft
4 0.000292 0.00146 0.00292 0.0073 0.0146
6 0.000465 0.002325 0.00465 0.011625 0.02325
8 0.000739 0.003695 0.00739 0.018475 0.03695
10 0.00118 0.0059 0.0118 0.0295 0.059
12 0.00187 0.00935 0.0187 0.04675 0.0935
14 0.00297 0.01485 0.0297 0.07425 0.1485
16 0.00473 0.02365 0.0473 0.11825 0.2365
18 0.00751 0.03755 0.0751 0.18775 0.3755
20 0.0119 0.0595 0.119 0.2975 0.595
22 0.019 0.095 0.19 0.475 0.95
24 0.0302 0.151 0.302 0.755 1.51
Making your own cables is inexpensive and a good way to go if you are handy with a soldering iron at all. Wire can be either briaded or solid. Wire is normally briaded on lager wire sizes (smaller gauge number) because solid wire is much less flexible and harder to work with. It is best to tin the ends of the braided wire ( you heat the wire with the soldering iron and then touch the solder to the wire and the heat of the wire melts the solder and is is basically absorbed by the wire).
A lot AVRs and speakers have connectors for bare end connections; It is good to strip about 3/8". much more is too much and can cause shorts it the bare wire touches the other connector. Less and you might not get a good physical connection between the bare wire and the connecting post.
You can connect Bannana (connection and soldering) or spade plugs (crimping). The bannana plugs require soldering for good long term conductivity.
You can buy cables at all different prices. Shielding is good ( one conductor isi nthe center and the second conductor is a braided circle arond the first) as well as twisted pair wire. Wire size has some importantce but going to 10 gauage over 14 gauge or 12 gauge is a waste of money. Also there is very very little difference in properties for audio cables between a 10$ cable and a $1,000 cable. Gold is a better conductor than copper and some tips on the ocnnectors are gold plated. Relook the table above and come to you own conclusion.
If you really want to do an unbiased test get a basic red or white audio cable from radio Shack or the cables that come with satellite or game systems. The buy some more expnsive monocables or blue jean cables. Have a friend hook up one set and lsiten too them. Then have the hook up the other set. Without looking see if you can tell which was the more expensive cable. 99% of the time you won't be able to tell.
Good Luck and Wire On!