I don't know if I missed something, but the last time I configured a comparable device (the Dell XPS 13) the prices for storage upgrades were basically identica

I don't know if I missed something, but the last time I configured a comparable device (the Dell XPS 13) the prices for storage upgrades were basically identically. The overall configuration ended up being 200€ cheaper than the Apple equivalent, so not really worth considering the effort it takes to completely switch platforms.