LibreYLoco

I recently bought a 2002 Audi A3 and was hoping to replace the stereo with a bluetooth one (possibly this.. http://www.halfords.ie/webapp/wcs/stores/servlet/product_storeId_11101_catalogId_15551_productId_918067_langId_-1_categoryId_212600) However, I was quoted a price of €100 for installation and additional parts on top of the head unit price. I have looked up a few videos on yourtube and it doesnt seem like the most complicated thing in the world. has anyone installed their own, and have any advice or know what they are trying to charge me for? It was all very vague in the shop. adittionally if anyone has any advice on where or what to buy in terms of a stereo that would be greatly appreciated too. All i want is something with Bluetooth, a CD player, and a usb port. Thanks...