The primary performance characteristic that you want from any cable, IMO, is that the cable changes or alters the signal as little as possible. (There is another school of thought, however, that cables should be chosen to modify some aspect of the system's performance -- in effect making them act as "tone controls".) Having said that, the most important electrical characteristic in a speaker cable is low impedance (even if the capacitance is a bit high) -- although ultimately your own ears will have to be the judge of what you like.
There have been a number of threads on the topic of speaker cables, and I suggest that you look in the A-gon archives to see what comments have previously been posted. For now, I will simply share my recommendation for the two best "budget-priced" speaker cables (based on personal experience):
1. the Alpha-Core Goertz MI2 (copper)(see their web site for good info about these cables);
2. the Kimber 4TC or 8TC.
Both of these wires offer excellent performance for their price, and can be used in single wire or bi-wire configurations.
Here are the links to the web sites for both of these cables:
1. Alpha-Core: http://www.alphacore.com/goertz.htm
2. Kimber: http://www.kimber.com/Products/LoudSpeakerCables/default.aspx