Your budget of 2-300$ is fine for springs, but you gotta consider upgrading your shocks & struts while you're at it. Lowering the car with stock stuts and shocks usually reduces handling. Also, installing springs is usually around as much as installing a complete suspension (shocks and struts), so you might as well take advantage of the labour you're paying.
For springs, if you're gonna insist on using your stock shocks and struts, i'd get either Eibach or H&R sports (not race).
If you're going to change the shocks and struts too, i'd probably get the DDM coilovers, although apparently some of them have been problematic.
If you just want a temporary solution to make the car lower, i'd cut the springs, but everyone is going to try to tell you that your car will somehow explode if you do that. That's not the correct way to lower your car though, but its a nice way of mocking up how it will look like, and its usually cheaper to do.
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2002 TiAg M3 6mt
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2006 YZF-R6, black, ohlins, pazzo, BMC, cat delete, vance hines csone, YEC racing tune,-1 +2