How much do iPhone's sell for shortly after release?

Hey guys just looking for some advice on my next device. My contract is up and I'm looking for Sony Honami (i1, z1, etc), Moto X with a wood back, or maybe even wait until HTC One (2?), Galaxy S5, or Nexus 5. What I'm thinking of doing is buying a iPhone 5S to sell on Ebay and use that money to buy the newly discounted Nexus 4 and wait to use the rest of the money on a new device. Does anyone know how much I would get off a 16 Gig, 32 Gig, or 64 Gig? I didn't pay attention when the iPhone 5 came out. Which is the easiest to sell with the best profit margin? How soon do I have to get it to be able to sell on eBay before availability kills the profit margin?

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