Well without opening cable wars part 9,605, I agree that with TT phono outputs being a weaker signal there is more of a reasonable theory behind getting a reasonable phono cable. How about a well thought of Linn Black (fleabay for around £30)? As far as I'm aware this was actually developed by Linn as a good quality TT cable for the LP12 for the reasons stated, so it should be just the ticket for your needs but without at the same time breaking the bank.
Whether it would actually improve on your existing cable is another question entirely, but you wouldn't loose much by trying out both and then re-selling the one you personally think sounds inferior...