A nice and effective way to look for cheaper parts. (at least in North America)

[Rustam]

.
Say, you need to get part number 26111105398 . I type " bmwbuddy 26111105398 " into google search line and get a list of various vendors that sell this part, ordered by price. Hence, we find that this part costs about $14 at amazon.com , $16 at Amazon.com , $19.19 at autohausaz.com etc...

here : BMW 26111105398 Drive Shaft U-Joint | Compare Prices

[BigKriss]

Okay, good to know!

[shogun]

Works similar to bmwbuddy, here copied from the thread where I found it:
http://furiousmethod.com/
I kind of forgot about this site and was using Pelican most of the time because they were super fast to me but I was looking through my bookmarks I found furiousmethod.com.

How it works is you enter in a BMW part number and it automatically searches up to 22 different online parts retailers, and pops up a page for each with search results for the part # you entered. You can also customize which sites it searches.

I was all set to pay $155 for a Behr radiator for my 96 328i from Pelican with free shipping but I just found the same brand at bmaparts.com for $115 with free shipping! Then I found a working 5% code at retailmenot (code: SpecE30) so I'm getting it shipped for $109.43