Roller Rockers? Help please.

[VYPplater]

Hi im john and i know nothing about engines other than where the fuel goes so...
Ive been informed that i should get higher ratio roller rockers as a good bang for buck investment at far as performance so 1: What do they do ? ( I like to know what's making it go faster)
2: What sort of prices am i looking at to get them put in in the perth area( as close to Armadale as possible)
and 3: If they are worth it ? personal experience is preffered.

[VS-S-PACK-UTE]

mate i put 1.95 ratio rockers in my VS commy and YES they are worth the amount i payed $ 500 something, revs climb higher very quickly. unsure on exacty how it makes it go faster but at a guess it'd b something to do with the higher amount of fuel/oxygen intake and exhaust due to the increased lift??? someone correct me if im wrong. unsure of how much u'd pay through a distributor, check ebay though coz they pop up on there a bit.