There are quite a few good bang for buck tyres around. If you spend around 220 per corner, you should be getting a good set of tyres. Stick to the main brands, avoid budget ones such as Nexen, Nankang, Silverstone etc. Run-Flats have their advantage but because of the thick sidewalls, they are not a confortable tyre and expensive. Philips Crystal and Diamond are not ADR compliant and give crap visibility so avoid those. If you want to lower the car just for looks, you can just have the springs changed. If you want improved handling you need to do a little more such as shockers plus springs plus sway bars.