Can I get a blackberry in a phone shop then just put my sim card in it?

[Aida]

Preferably not too expensive... and not black.

[geeth]

HI yes you can use your old sim in the new blackberry phone only if it is unlocked one .Else if the blackberry phone is locked to some other network provider then until you unlock it you can't freely use it with your sim .You can easily unlock your blackberry mobile using sites like UnBBlock.com here they are providing unlock code for all blackberry mobile models at reliable cost .