Thermaltake is going to be louder than it says (Volcano, ugh). Thermalright heatsinks, the XP/SI ones espeically, appear to do very well with medium/slow fans, even overclocking (haven't seen actual SI-97 vs. XP-90 benches, but the SI-97 vs. HT101 w/ Panaflo M is very telling).
Thermaltake stuff isn't really bad, but not as good as they advertise. Thermalright and Zalman are absolutely excellent. Thermalright will be a bit more, but offer better perfomance (~$50 w/ fan), where Zalman might get you a little quieter ($~35). Thermaltake is middle-of-the-road and gaudy.
If you want significantly better than retail, you'll need to spend $30. It really is that simple. The good news is $30 now does get you better than $60 did a year ago.
BTW, for stores, try SVC and case-mod.com (IMO). Now, if TR would make something like the SI-97 with provisions for all four current sockets, I'd be in heaven, as then $40 or so wouldn't be too bad--it would carry over.