TREX is about double the price of Redwood.
Here is a good article for you:
also check out the second entry on this page:
If you use Redwood or Cedar, You will need to apply a good UV (ultra violet) resistant sealer on completion of the deck and every 1 to 4 years afterwards.
Both decks should give you 20 years or more of good service unless abused.
TREX maintenance is going to cost significantly less, the installation fee will be cheaper, and you won't have as much worry about damage, weather, kids, insects, etc.
TREX will save you money long-term.