How much is my Peavey milestone bxp bass guitar worth?

I have a peavey milestone bxp bass guitar and I'm selling it along with the amp which is an ultrabass bt108. Both are pretty much brand new, I've played the bass a couple times and then i just lost interest in it. Now I'm selling it to this kid for $150, but then I looked up the price of the amp and I'm thinking that's a little cheap. So yeah how much would be a reasonable price to sell this for?