Which JG Mp5 sd5 do I buy?

The one mp5 sd5 is on http://www.kapowwe.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=jg068&Category_Code=Jin-Gong&Store_Code=R. Its a new advanced version of the gun. This one costs 140. The other is on http://www.airsplat.com/Items/ERM-JG-M5S5-068.htm. This one is only 90. Which one is best or would be a better buy?