MINI Cooper S Balancer Question

My wife's '04 S started making noises and they seemed to be coming from the idler pulley. I bought a new idler assembly, fixed idler pulley and belt from NAPA for $201 out the door. I opened the boxes at the store and discovered that ALL of the parts were from the OEM. Tom Bush wanted $279, $89 and $49 for the same parts. It turns out that it was the harmonic balancer which in very short order disintegrated, taking out the inner CV boot. The local MINI guys (Tom Bush) want >$400 for the balancer, $12 for the bolt and ~$40 for the seal. My options are mail order a stock balancer for ~$300-$400 depending upon type and an Alta, undamped pulley for <$150 shipped. Does anyone have an opinion on using the Alta pulley in the stock diameter? Suggestions are appreciated.

Avoid the undamped Alta. The engines have balancers for a reason. ATI makes a more durable replacement: http://www.atiracing.com/products/dampers/charts/dammini.htm

FWIW, the R&R requires some special tools (casually noted in the install instructions for the above).

I remember the stock harmonic balancers on these are a source of constant trouble but I don't remember what the solution is, if there is one...

Engines do have balancers for a reason and running an unbalanced one will create problems that will make you wish you only had to change a crank pulley...