Is there an after market replacement air filter for the M2. I'm not about to give HD $43 for a CS $10 air filter. I'm not a fan of K&N, I just want to toss the old filter and put in a new one for under $20( which I regard as twice what it should cost) anyone found something close that will work for cheap? I went to the knowledge vault but all I could find was ways to spend $$$$) Thanks