I have a Snap-on Solis pro& a ross-tech vag-com....the $350 ross-tech Vag-Com is By far better for vw/audi than the snap-on($7000)....
I am checking out Programa.com for Volvo, Benz, and other European brands...
I am sure there is a good PC based OBD-II for Generic/Global diagnostics, in the $300 range....
91 miata....I think it take a paper clip....02 honda, generic is awesome, except for air bags& abs...American trucks Generic obd2 will also work well......
Any programing that needs to be done will take a serious piece of equipment....$1000-2000 per manufacturer....