how much do you want to spend, it'll probably be a bit more. look at a build thread and add up the prices that you can get the bits for.
built a mk2 1.8T with a mate for them to do a rally with a £500 budget ( including buying the mk2 and all bits for conversion ) it's possible to do it but bloody hard work. likewise you can spend 5k easily if you wish to.
3.5k sounds like a good number at the moment