There was another post (some time ago) inquiring about another NVIDIA Tesla card, possibly the K40. The consensus was that despite the age, it does benchmark similar to modern cards, despite the high power consumption.
Keep in mind; however, that due to the power-consumption, it's easy to heat-up which results in *throttling* down the GPU. Therefore, in consideration for the high power consumption, you must be sure you add supplemental cooling. Either on the card itself or adding some high-power on-demand ancillary cooling.
Keep in mind the K80 also has 2x 12GB RAM (it's essentially designed as a 2x GPU on a card). Because GPU memory is so crucial to Metashape, you should notice that for the price, you'll get great bang-for-your-buck with the K80, providing you don't mind compensating for the power/heat issue.
If you do go with a K80, will you report back and share your real-world experience? Thank you!