Here's my .02 since I used to do this a lot in my previous life:
A cheap cable and an expensive cable basically work at the same speed. But a flaky cable, one with broken conductors or poor termination, will cause CRC's and other transmission anomolies on the attached Ethernet segment. Then you will see some tangible network slowdowns, as indicated by Spidey. So what you need to measure is reliability -- not speed. A cheap cable may work fine for the first couple of months, then begin to degrade. You do not typically see this with quality pre-made cables. And quality pre-made Catgory 5 patch cables are stranded and do not exceed 10m in length. Anything longer isn't within Cat5 spec (which makes provisions for a total of 10m of stranded patch cable), but if it is made correctly it will still work and be fine for somebody's home network or small business.
Another factor in the cost of a cable is whether it is PVC-jacketed, riser-rated, or plenum-rated. People who aren't running their cables in a ceiling where the return-air system is shared don't need plenum-rated cable. If they aren't running cable between floors of a building, they don't need riser OR plenum-rated cable. Plain ol' PVC is fine for most applications. So I'd rather have a quality stranded PVC patch cables than some cheaply made plenum ones. Conversely, you sure wouldn't want to run PVC in a place where it violates fire codes.
Okay, so to answer the original post: I prefer a quality cable that fits the application -- I would usually spend a maximum of $12 for an amp or panduit patch cable from Graybar. And I would buy the cheapie Big Box O' Blue Cable (solid) for most small network installations. But I always paid extra for good termination -- no RJ-45's! Only Panduit or Ortronics modular gear, no matter if it was just two or three cable runs.