How much would a new oil pan be?

no engine size listed in your question or no Model,there are 3 diff models and 3 different engines >>2.0L>>2.3L>>2.3L Turbo unless it's a Mazdaspeed3 and that is a 2.3L Turbo. Mazda3 and Mazdaspeed3 are different,look up your part on local parts store website like Advance Auto and then look it up on rockauto.com,compare prices....