Market place opportunities

I am in need of thousands of cards to complete my sets so i love the idea of the market place opportunities. the problem i have is on the filter. when i click on my purchase opportunities, (i will use Byron as an example) it says he has 19 cards i need for $1563.38. however i found by clicking on his profile, there are infact over 2500 cards that i need that he is selling. to me that is a great place to shop for the cards i am looking for but i wouldnt have known this from the portal page.