Your best bet is probably to make your own.
Find a high quality NVMe drive and put it in a USB enclosure.
If the USB ports or anything other than the drive fail, the data is easily recoverable.
Given your use case, buying an external drive is probably fine, just don't get one from SanDisk.
Give it a decade and economies of scale, and maybe it will get it down to twice as expensive.
That sounds like a good deal for whoever ends up buying unity
If housing was true free market, demand would drive new construction.
But its not, developers are artificially constrained into building inefficient single family homes, or giant luxury condos due to zoning and other hindering regulations.
Removing these regulations would allow new upstarts to vastly undercut the current market leading to more affordable housing.
Recent controversy over an absurdly high failure rate.
https://www.theverge.com/22291828/sandisk-extreme-pro-portable-my-passport-failure-continued
Might be fixed now, but i wouldn't gamble.