i dont know what to buy about arduino 
i need something less complicated (not like xbee shield and bluethoot shield) 
and i also need a shield in a cheap price...
if you are gonna give me some suggestions, dont forget to put the detail about the shield
It might help if you would add detail about what you are trying to accomplish...?
Sounds like you are after RF Comm's- if you need simple 1-way comm's then parts like this
http://www.robotshop.com/433mhz-high-sensitivity-transmitter-receiver-pair-rxa30.html
will do the trick, with Virtualwire to perform Tx one end and Rx on the other
Works great, inexpensive way to get started with RF comm's.
I am particularly fond of these little devices:
http://www.hoperf.com/rf_fsk/cob/RFM12B.htm
They have a simple SPI interface and work well. They are not as easy to use as the Rx/Tx modules using the virtualWire interface but they give you that extra control.
This shield should keep you busy for a month or two and you will learn lots of new stuff.
and here we are talking to ourselves again, the OP having made 1 post & then disappearing ...