You might need to be more specific about the stock photos you are selling.
Besides, having the models release is VERY expensive - not sure why you are selling so many photos, released, under such a low price.
Even when it sounds like a super deal, the truth is that if I don´t know what the stock photos are about, I don´t know if they will be worth for me.
For example, if I buy you pack and they are all 500 photos of 500 different models all doing random stuff - I won´t be sure what to do with that.
But, if you are selling 500 photos that have:
10 photos food related
10 photos tech related
10 photos business related…and so on, now that sound like something I might be interested in.
I know I´ll be purchasing a variety of topics and one day maybe, some of those images will be relevant to a project due the diverse content.
So far 500 photos with no info about the content, might go under the radar.