If you only have a budget of 20K, look for a car around the 15K mark, that way you have extra for insurance, rego, miscelaneous repairs, services, minor mods etc...
Don't be one of those ppl who spend the whole lot on a car...whinge tht they can't afford insurance and then stack it and post a thread on here expecting sympathy.
Get insurance quotes first before purchasing...not vice versa.