I usually use my own colours. I use her hints (this is dark, that's light, these need to contrast - she is really good about providing guidance I think) and usually start with my stash. This year I went all out, found a print I loved the colours of and picked my 4 colours from that (the original print will be the backing). Even when I do Bonnie's colours, I just use them as a guideline. I never get the paint chips (tried once, failed miserably). I prefer to pick what I like together. So if she's using teal & salmon, I might end up with a greener teal than hers, or a pinker salmon - but as long as I like the 2 colours together, that's what matters.
For the quilt you are trying to replicate - that's what I would suggest. Get the fabric you are sure of, then audition a bunch of grey/cream/blue and see which looks best in the grouping to your eye (or the eye of the fabric shop staff - they are usually a great resource for colour matching if you have a local shop).