Depends on what size rims you are running and on what car they are going on.
Most later model evos will run a 235/45/17 semi as this is stock rolling diameter, if you were to go a slightly wider tyre or go from a 17 to an 18 you would run a lower profile to maintain the rolling diameter.
Budget and semi slick are two words which generally don't go together, it's the old adage you get what you pay for.....kumho make a lower priced R tyre but they are far from fantastic.
I believe yokohama ao48's have dropped in price a little now that yokohama has released the ao50, they are a very good tyre.
If you are planning on doing just the odd trackday here and there it sometimes pays to scan the classifieds and keep an eye out for a secondhand set, sometimes you can score tyres with quite a few laps left in them for a fraction of new price.