I find valuing pins so hard, because I know what people are really asking is 'How much would I get for selling it?' and that's...not always consistent or realistic. I suggest if you're going to assign it a dollar value, and one cannot be found for sale or sold at all, that you value it a bit higher than the average pins in the same category. For example other 2004 valentines day pins with Ariel & Eric are selling between $20-$40 - this one appears to be harder to find, it was also sold overseas, and it's LE 1000.
I'd probably value it at $65 - Ariel is popular, it has Eric and Sebastian on it, it celebrates a holiday, it's hard to find, and it's dated. Other people are offering to trade it, but not as many as people who want it.
Though take what I say with a huge grain of salt because I just got thrown back into the chaos of 'valuing' pins, I'm wondering what other things people look at when deciding and if my logic in applying a value is totally skewed.