I think this is the story:
The Scottish purchases cover a 15 Month period to March 2021 whereas the DHSC purchases cover a 6 month period to July 2020, which is to say the peak of shortages and thus the peak of prices, on a simple pro-rata basis that equates to £120m, or about 1% of the DHSC spend over the period.
On a per capita basis, I'd expect Scotland to have needed about £1bn worth of PPE over the 6 month period, and thus they appear to have sourced about 90% of their PPE from the DHSC. In reality I suspect they were almost completely reliant on the DHSC during the early stages of the pandemic, and the vast majority of the £300m spend was after July 2020, i.e. after the initial shortages, hence how the buyers were able to go to China to check the suppliers, an option obviously not available to the DHSC in March 2020.
So it's not a fair comparison at all. The Eye is comparing emergency purchases during the initial crisis with top-up supplies acquired at leisure once the shortages have passed, even then NHS Scotland seems to have been 80%+ reliant on the DHSC.
A fair comparison would be to look at what the DHSC was paying after July 2020, but then that doesn't sell papers, in the circumstances, it seems creditable that the DHSC was "only" paying a 20% - 30% premium for the supplies.
It's always worth checking these stories, they're almost always misleading.
Edit:
First paragraph got overwritten by the link, I've had to rewrite it.