For good gory effects you'll need to be able to make convincing fake body-parts which you can mutilate, blow up or what ever your heart desires.
That is only a matter of proper attention and some craftsmanship, it can be done at low costs.
Let's say you want someone's hand get shot of at the wrist. Make a fake hand out of rubber with thin iron-wire in it (so it can wiggle a bit) and paint it properly. Attach this to a wrist made of plastic clay with pre-broken chicken-bones in it and some fake blood in a thin capsule (easily made with simple water based paint). Place a tube that ends in the 'breakingpoint' of the wrist and fit the other end to a compressor.
When you pass a burst of air through the tube, the wrist will splatter apart with blood flying around and sending a trembling hand with bones sticking out of it through the air. You can also use a saw or blade on this setup, and won't need the airburst then. Just make the prosthetic long enough to keep the actor out of harm's way.
Same can be done with feet, knees and such. Heads are a greater challenge though.
Not really original effects eventually, but still cool if you can pull them off low-budget.