I don't know for a fact, but I would guess that it's worth very little. Less than $5 probably. The trailer is readily available on DVD so it's not something that you can't watch anywhere else, and the only difference between what you you have and someone else putting the trailer on a VHS tape is some sort of label.
If you had the original trailer, that would be worth a little bit, but you can't sell them on eBay anymore. I used to, but they always bitched about it being studio property, even though you just toss them after you're done in most cases. It wasn't worth fighting, that's for sure.