meh, i dont really agree with the above, but everyone has different tastes...
i have about 8 cheap regulators ($32 harbor freight ones, or ebay) and they all work just fine. there is no reason that the 3 components inside them wont last just as long as the same 3 components in a $80 regulator. and if you abuse either cheap or expensive ones, they will both break just the same.
the main things that expensive ones have that cheaper ones may not are nicer gauges or adjustment handles (cheap ones often have poorly labled gauges and an adjustment screw instead of an actual handle). nice regulators also have a cage around the gauges for protection. its up to you what you want to pay for though.