If it's very important to you (like it happened to me, my last name domain was expired and I wanted to grab it at all costs as the previous over rejected any offers to sell) you should consider some backordering services. While there is no guarantee, you can certainly have more chances. If the expired domain is something popular then it will end up in an heated auction which, depending on the domain, can end up sold for large amounts on money.
So only you know how much that domain is worth and how far are you willing to go.