Display variable within a variable.

I know I can do this by splitting my error message, but I'm wondering if there is any way of doing it by display a variable within a string contained in another variable. I have all prompts and error messages stored in a database table, fetch them according to the language required, and display them by using this general form: echo $arr_lbl[ lbl_Usernam ]. This would display "Username" for English, "Benuztername" for German. If a user's bid fails, I call this: echo $arr_lbl[ lbl_cMsgBidFail ] which contains this text: "Thank you for your bid. To be accepted it must increase the previous bid by $yMinBidIncr. Please adjust the amount and send it again." $yMinBidIncr is the amount by which this bid must exceed the previous bid. What happens, of course, is that $yMinBidIncr doesn't exist when the prompts are fetched, so resolves to "" and does not display. Is there a way of inserting this into $arr_lbl[ lbl_cMsgBidFail ]? Miles Thompson