20" white imac screen replacement

heya,

i want to replace my lcd on my white 20" imac, i know i have the samsung panel, cause that is what i saw when i changed the hard drive, but i didnt write down the model number, but from google, i have found 661-3895, but also i have noticed that some of them have a lg 661-3881. does this mean that they are interchangable? and where is the cheapest place to get a new panel, or a refurb lcd.

btw i am in australia, but i will order from oversea's if needed.

thanks