Replacement Oven Seal

I think you also need the black silicone stuff too, or I did when I tried it. And it turned into a right mess. (The rubber doesn't just slot into a gap like a fridge door say).

That being the case might be worth investigating stove rope, you don't stretch this so it's easier to fit. (edited)

Have you tried googling 'oven spare parts'? A lot of sites e.g. espares (other sites are available) sell suitable replacement parts for a fraction of the manufacturer's price.