Looks like KO Performance is pretty cheap. But the pump is out of stock!
http://www.koperformance.com/
$403.15 - 11517632426 for the pump
$77.48 - 11537549476 thermostat
$3.72 - (3) 11517602123 bolts
Ebay has parts too
$403.99 - 11517632426 for the pump & (3) 11517602123 bolts
http://www.ebay.com/itm/BMW-OEM-FACT...a29db3&vxp=mtr
$56.13 - 11537549476 thermostat
http://www.ebay.com/itm/NEW-FITS-BMW...7a0809&vxp=mtr
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2008 BMW 335xi Coupe 6-speed, 12.8 @ 107
2000 Chevrolet Corvette Z51, 11.4 @ 123
2005 Saturn Ion Redline, 14.1 @ 100 (sold Jun-2013)