I have an aging but still functional Bosch UM-3 stand mixer.  And I wanted to replace just the plastic bowl for it.  It took a surprising amount of effort to find the right place, but in the end, www.mykitchencenter.com came through.  The bowl itself (sans hardware which is still perfectly good) is only $24.95 and shipping to Hawaii another ~$10 via USPS Priority Mail.  Here's  the parts link:  http://www.mykitchencenter.com/Details.cfm?ProdID=615

I have no affiliation to the company, just reporting it as a satisfied customer.

  aloha,

Dave Hurd, Hilo, Hawaii