It’s worth paying a few quid for build quality, rather than buying crap that’s going to fall apart after five minutes. Other than that, as others have said, quality (in terms of signal quality) is largely irrelevant, in contrast to the analogue interconnects of old.
HDMI has tight specifications that define how the cable (and everything else) performs. If a cable meets these specs, it’s good whether it’s a fiver or a hundred quid.
One thing of note, the HDMI spec gets revised. The revision of cable / component will till you what it supports (note – this is not the same as what features it has actually implemented). For instance, 3D TV requires HDMI 1.4.
I think the PS3 uses HDMI 1.3 (google thisto be sure – I’m in the Xbox camp so I’m not 100% sure off the top of my head). Whatever it is, get a cable that matches or surpasses it.
So in summary, you want the cheapest HDMI 1.3 cable you can find that isn’t made out of tinfoil and spongecake.