If you buy name brand springs from ebay, specifically for your car, you got a good deal. If you buy an unknown one-spring-fits-all-cars-brand, it may likely be a disappointment...

Since I do both: install aftermarket springs as well as modify stock springs, and frequently do what people say is impossible,
If I can be of help with your decision, get back with me.

About 1 1/2" works well for a street lowering for lots of people I have done work for. When a car is lowered, sometimes a camber kit is needed.
A proper alignment is mandatory to save your tires.-Bob