I am also strongly value-oriented when it comes to audio gear, so I'm not sure that I'd recommend adding new power cords at this stage in your system. However, if you want to look at this anyway, then check out HCM Audio (www.hcmaudio.com). They have been running a clearance sale on several brands of power cords, including AudioQuest. I bought AudioQuest power cords from HCM to replace the stock cords on my Bryston amps and pre/pro, and found HCM's price and service to be very good.
Interconnects are a different matter. Upgrading your interconnects is much more likely to yield audible improvements to your system. I have used a number of lower and mid-priced interconnects in my system, and have recently settled on Super Silver interconnects from HomeGrownAudio (I am using 7 pair in my current audio setup). You can buy kits for HGA's interconnects -- the kit for the 1 meter Super Silver, for example, sells for $59. All you need to assemble the Super Silver interconnect is a soldering pen, electrical circuit tester, the ability to follow directions, and a bit of skill.
It wasn't clear from your post if you also wanted advice on speaker cables. If you do, then I can make no better recommendation than Kimber Kable 4TC or 8TC. This cable is certainly one of the best products at (or anywhere near) its price range, and has even been recommended by The Absolute Sound for use in quite expensive systems. I have been using Kimber products for years, and think their moderately priced interconnects and speaker cable are genuine high value products.