Your standard benchtop minifuge should be able to give you 16,800Gs, just shy of your stated goal. I'd look to eppindorf, VWR or thermo for good fuges that work in that range. And example: [Only registered users see links. ]
If you do need the extra G's you're going to need some sort of ultrafuge. I'm less familier with the option, but they are available in models that go anywhere from 20,000G's right upto the hundred-thousand-plus range. As you'd expect, these fuges are indescribably expensive. I'd look around your department for someone who has one, as unless you need an ultrafuge a lot, they're really not worth buying.
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