I am afraid that I am not as helpful as it pertains to quality comparison. I happen to have ordered from all of those companies, but tend to source different items from each. That doesn't really allow for much side-by-side comparison.
I am a numbers geek and wanted to address your cost comparison. My analysis is a bit different. While I agree with your assessment of the retail prices, I find that the shipping offsets that greatly. With respect to shipping rates: Camden Grey usually runs comparably high, with Brambleberry being more reasonable, and Mad Oils downright cheap. (Mad Oils' current shipping rates are $4.50 for orders less than $10, $9.99 for orders up to $125, and free shipping for anything over that!)
I received an order from Camden Grey today , but placed it with them primarily due to their New Year's sale. Mine was a $300 order that would have incurred a shipping fee of more than $60 without the $58 promotion. I know that oils and butters are heavy, but adjusting for shipping, their prices are actually 20% higher than they appear. That being said, they do carry some items that are difficult to find elsewhere.
I have never placed an order with WSP despite their popularity. It appears to me that most are enamored with their free shipping (including my incredibly broke sister-in-law). However, whenever I have duplicated my cart on WSP's and BB's sites, the total (including shipping) has been cheaper from Bramble Berry. I live in Austin, Texas and assume that this might not be the case if you are even further away from WA than I am
I do think that Mad Oils is pricier, but like their products and really love their customer service. I have never failed to reach a representative when I called. Bramble Berry also scores high for me there. While I have often needed to leave a message, the call is always returned by 6:00pm the same day. Any calls placed to Camden Grey have never been returned. However, they have been surprisingly responsive to my emails (despite what I consider to be an off-putting FAQ page).
In short, I factor shipping and customer service into my vendor preferences and might reverse your rankings based on that.