This is tricky because a strangifier exists here. Its value is outdated, and it rarely sees sales. The last sale was half a year ago for some 35-40 keys. This covers more than the gap between the lowest seller on the non-strange variant and this sale. Given that the strangifier was not available for purchase at the time this sold (nor was it for 4 months leading up to this sale), anyone that wanted a strange one had to buy this one. Note that half of these are strange, but since the second most recent strange one moved over a year ago (and the other ones don't list any sales, so it will have been several years, if at all).

Given that this sold while the non-strange variant was listed for less, along with the value of the strangifier and its lack of sales & low sales frequency, this will be okay here. Note that in general, the non-strange variant should still be priced if a strangifier exists. Exceptions exist in specific situations, and this particular situation warranted one of those exceptions.