Does it make sense to buy an iPhone 4 now?

Question

iPhone

Good day!
Relatively recently, there was a demand in the second mobile device. But I don’t really want to spend 7-10kr for another smartphone.
And a friend today said that he decided to sell his former apple tree 4 for a modest price - 5 Russian tubriks.
I know "both": the person took care of the phone, and the phone itself is not Chinese, but the original. Not broken, all native, outwardly looks good.
So the question is: is it worth it? In fact, I don’t know - is its price at the moment bu, is the price / opportunity ratio normal?
In general, I'm not demanding ...
The former owner of 4s was satisfied, now he is on the "galaxy" c3.
The requirement is small: the screen is no more than 4 inches, the smartphone is exactly, 3G support, navigation should be in full openwork (gps, glonas - or whatever), the screen is good, the battery plus / minus is good, support for a bluetooth headset is required ( such a headset ( LG Tone) , by the way, need a review?
Will be used mainly as a backup phone, navigation device, entertainment, additional phone for visitors)
Thank you.

Answer 1

if you have not updated to iOS7 - then you can take

Answer 2

Well, yes, for 5k you can take it as a second phone.