The version of Sonnet's Breakaway Box which Ars Technica tested is priced at $300, for that you get the housing with a 350W PSU inside that can handle a GPU of up to 300W.  There are two other models, the Developer Edition which shipped with Apple's External GPU Dev kit and a higher powered model which can support cards that require up to 375W.  AMD worked with Sonnet to create an optimized driver for this enclosure which has enabled them to retain more performance than NVIDIA on this Thunderbolt 3 enclosure, however all the cards they tested did show performance degradation compared to a GPU inside of a desktop system.  On the other hand that is not what this device is for; it is to enable a laptop to play high end games and in that it does succeed.  Check out the full review here.

"The Breakaway Box is best described as functional, consisting of a simple steel chassis and vented side panels (neither of which, sadly, feature proper dust filters), with a power supply, 120mm fan, and a single PCIe slot inside."

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