Wash, Stain and Finish a deck. DIY or Hire someone?

We just got an estimate and it came in at $700, I estimate costs to be around $400...

Anyone have some opinions on this?
Update: Sorry, I estimated the diy costs to be $400.... I'm wondering how hard it will be to make it look good...

I HATE doing this kind of work, but my wife seems to like it... good answers so far!!
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