algozone open cart template modifications

I have an open cart website which I have currently set up with an Algozone template - see Algozone website jewellery open cart template. However I have a set of modifications I wish to make including changing the colour of some of the buttons and the background colour to the header of the homepage etc. I also wish to change the colour of some text and make a few other edits to the site including adding £ signs to the prices in the flash boxes etc. I understand that this isn't a full list of the changes I require at this stage but am interested in knowing how much someone would charge fir this work before agreeing the list of changes and final price. Thank you