I've used Kijiji for buying before with no problems. Purchased couple of iPhones. Did it at Apple Store or my mobile carrier so I could make sure all was legit. Even did a trade one time of an iPad for an iPhone. Have to be careful, just like buying anything thing from someone you do not know. Meet in a public place and if the deal is "to good to be true", it most likely is.
I always done my transactions at the Apple Store or my mobile carrier. Will be looking for two iPhone 5s this week for Xmas gifts on Kijiji, so no issues here using them. Kijiji if I am not mistaken is owned by Ebay but does not have the same rules as Ebay. It is closer to Craiglist, but in Canada only.