Feedback from birdseed manufacturers is variable, I have to say. I'm a long term vegetarian, and found the website healthysupplies.co.uk from another prepper, used them for about 6 years now.
https://www.healthysupplies.co.uk/edible-seeds.html
As an example, 2kg of organic pumpkin seeds, which I use in my morning porridge, is £13. I think that's good value. And I've never had a problem with what they sent, though their delivery windows aren't exactly tight, that's down to the transport firm, and Healthy Supplies must be a comparatively small firm. I've got an order in with them at the moment, should be delivered in the next 3 days.