Vastly improve tone, on a SMALL budget?

[Fang]

So my amp sounds pretty harsh/sterile (Marshall AVT20), I have an RGT42 with an Evo2 b/Fred n, and I just sold my GSP-21. The processor wasn't exactly what I was looking for.

Let's say my max spending is $200, how could I vastly improve the tone of my Guitar + crappy amp setup? Be it to buy a better distortion pedal (I was thinking a Keeley), an EQ, a compressor, etc.