Lythinca, please do a little more reaserch next time before providing advice
CAS (Canadian Airgun Supply) is the name of the importer that import all clear G&G products to canada.
They divide their products into three levels of quality.
The bottom is the Rec. - a rec M4 is $260
The middle is the standard - a standard M4 is ~$300
The top is the Advanced - an advanced M4 is ~$350
Most people will tell you the rec isn't worth buying, and I have to agree, for only about forty dollars more, you get a much better performing gun.
In fact, if you can afford it, i would do with the advanced, or if your willing to spend a few bucks more then the advanced, Go with the SRC Gen III
Below is a thread comparing the REC to the standard.
Amos, the guy who did the indepth reviews is a well respected gun-tech here. He knows what hes talking about.
http://www.airsoftcanada.com/showthread.php?t=88937