im looking for some one to customize my customize text opion

[robchef]

what i want to do iw where a customer write there text in a box and it goes on the product for them to see it before they by and if they select to but it send it thought the pay cart to me bit like this website does

http://www.zazzle.co.uk/cr/design/pt-zazzle_embroideredshirt/?customize_it=true&pd=231415490605085992&qty=1&get_started_dialog=false

if you click on there custiomisze option you see what im trying to do some think like this

how much would it cost to have a module modifered to work like this as i want to use it on lots of my products