How much would an iphone 4 be in july 2013?

I would like to get one for my birthday and i was just wondering how much they'd be.

That totally depends on which model you would like, gb size & which carrier plan you use.
At the Apple Store an iPhone4 is $449, 4S is $679, 5 is $799. I doubt prices will change much.
http://store.apple.com/...hop_iphone

Telstra has plans from $67 for 24 months
http://www.telstra.com.au/mobile-phones/mobile-phones/iphone/

Optus has plans from $30 plus $23 handset
https://www.optus.com.au/shop/mobilephones/iphone/iphone5?sid=con:mob:iph:til:0:img:iPhone%20topper%20976%20x%20382px:Launch#tab-features

You need to find out what you would like first then compare.