Javascript Malware on site – do I need to buy Surcuri?

Hello everyone,

A few weeks ago my site: nvg-rusland.com went live however, in recent days I have been getting reports from visitors then they get an malware warning when visiting.

I noticed a java app pop up appeared in chrome when I visited it so I restored to a previous back up, updated to the latest version yet when I ran it through Sucuri I recieved the msg:

<Known javascript malware.
Details: http://sucuri.net/malware/malware-entry-mwjsanon7

on various of my /?page=id= pages. (eg. page 4)

As a student I am reluctant to spend the $89 Sucuri charges for cleaning my site and I was wondering if I am able to fix it myself? I tried going through the various .php pages to see if I could spot any code that seemed wrong, but as my experience in this area is limited I failed to find anything.

I really dont want to do a fresh install as I heavily changed the coding of the theme and am worried I will mess it up.

Any help or suggestions would be greatly appreciated!
Thank you kindly in advance,
Eve.