Lou, I'd go the SB-900 I have two SB-800s and they are brilliant:D 
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			The other option would be to look for an SB-800 as they are well and truly old stock now and should be cheap as the SB-600
			
		
	
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The SB-600 is due a refresh. If I needed a third flash I'd be getting the SB-900.
 
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			One thing to note DON'T BUY A SECOND HAND OR DEMO FLASH.
			
		
	
  Flash units have a finite life and this has no reflection on the units appearance, it may look like new, but how many times it has been fired of and at what intensity and with what batteries.
 
For batteries, get 2700mA rechargeable ones, uses the 5 batteries so buy 10. This is a good vendor 
Servaas Products he's cheap and very knowledgeable.