Ashamed to admit but I sold all my formulae, thinking that I wouldn't need them since they were in my journal already... I can't buy them back from merchants (checked all the ones I could find, don't remember who I sold them to) so I was wondering if anyone knows whether there are any shops where I can purchase them again.

Otherwise, it's going to be hard without using any swallows :(

i'm surprised that the game doesn't account for this. granted, games like the TES will let you kill story-related characters and gimp your forward progress.

i'm also surprised that you're expected to actually hold onto every single formula, even though they get recorded in your journal.