So you just purchased your new HD television and the salesman tells you not to skimp on the lead and he will discount his £80 HDMI cable to £40. This happened to me recently and had I accepted the cable I would have wasted my money!
HDMI technology is digital so for normal installations low-noise cables simply are not needed. The maximum frequency the cable can operate at is the important factor. At the time of writing HDMI 1.4 is the highest specification and supports 1080p 3D 2160p etc. If you want to know more checkout Wikipedia.
Checking Ebay suppliers I can see a supplier offering a 1 metre HDMI 1.4 compliant cable with high quality connectors for £2.78 plus P&P or you can pay an extra £76 for some very nice retail packaging!
Some installations require HDMI with Ethernet Cables. These are not the same as just plain HDMI. As for the cost; my supplier noted above does either type for the same price!