I think to a point quality cables are a good thing, but the good news is, there are real nice cables available for cheap money...
As far as speaker cable goes I make my own fancy shmancy cables...
Buy some banana connectors
Amazon.com: Sewell Deadbolt Banana Plugs with Fast-Lock Technology, 12 Pair (24 Pieces): Electronics, some techflex
3/8 BRAIDED EXPANDABLE SLEEVING RATTLESNAKE TECHFLEX 25ft | eBay, some wire pants
Amazon.com: Speaker Wire Pants - 10 Gauge (Y Boot) -10 Pack: Electronics, and pick a good wire
Amazon.com: Karma Kable 50' Twisted 12 Gauge Speaker Wire: Electronics
make your own sweet wire cables..
As far as HDMI cables go I have really good luck with Blue Rigger, I currently have them in every HDMI component I own, 5 cable boxes, 3 ps3's, ect... I have 3 25 footers ran in the wall behind my TV to my media center, never have any problems, very good quality HDMI cables, read the reviews they are nice... And SUPER CHEAP $8 for a 10 footer!!!
http://www.amazon.com/BlueRigger-Speed-Ethernet-Supports-Return/dp/B003XM1WE0/ref=sr_1_2?s=electronics&ie=UTF8&qid=1350505961&sr=1-2&keywords=blue+rigger Not too bad for a nice hdmi cable, they have braided covers too, {not the inwall ones though, just the regular ones}
It is essentially Media Bridge, Because I order mediabridge Toslin cables and they come with the same shmpment in the same exact boxes, just different names...
RCA cables, Tartan, Acoustic reseach, and C2G are good, even the amazonbasics line is OK, The acoustic Research are my favorite though, a lot of sizes available and they are directional, so you have to make sure the signal is going the way the wire points..
For XLR cables I like Emotiva, they are about the best quality for the money, that I have seen, I used a couple of their Toslink too, but they are more money than media bridge and do the same thing, just look better....
So, I hope this helped, dont go buying $80 speaker cables when you can build 50ft of them for less than that, and dont spend more than $1 a foot on HDMI, blue rigger is my favorite, but monoprice has nice ones too... For the speaker wire itself if you dont want to go and make them yourself just wnat wire, that Knu Karma cable I linked you is really nice, I just got a roll the other day, very nice stuff...