Will the prices on the Iphone 5s and Iphone 5c drop when the Iphone 6 comes out?

Will the prices on the Iphone 5s and Iphone 5c drop when the Iphone 6 comes out?

Yes. 5s will be $99 and 5c will be free.

Yes, they will. Like a rock. Most iPhone users simply HAVE to have the newest version-leaving very little interest in older versions.
If you do decide to buy one (I wouldn't-for the money, Android devices are far superior) get one from a reputable dealer. If you use eBay, make sure to look at the negative feedback (if it exists). Recently I looked at a large volume, well known dealer of used phones-although their feedback was 95%, the negative feedback really told the story-customers being sent pink phones instead of blue, with no response from seller, being sold stolen/lost phones, etc. If it seems like a seller has a lot of dumb mistakes, then it's not worth using that seller, even with a 95% positive rating.

They already have. The 5c is now free & the 5s starts at $99 on a 2 year contract.