Have an expensive church building is not a problem in an of itself. We in the Catholic Church have some pretty grandiose churches ourselves. The difference is, ours are meant to focus us on celebrating Mass with Jesus Christ, Mary, and the entire Communion of Saints. It is our way of building a house for God that is truly worthy of Him. They are our gifts to Him. Just think of Christmas gifts. Do you buy your loved ones something inexpensive or something that you like or do you think of them, spare no expense and try to get them something that they will truly enjoy and thus display your true love for them?
The Mega churches, however, adorn themselves with items that glorify man instead. Large screen TV’s, fancy lighting systems, etc. How does any of that remind you of Jesus. These are just gifts to people, not Jesus.
One way to truly measure is to walk into the various church buildings when they are empty (of people). Which building makes you feel that you are truly in the presence of holiness and lifts your soul to be more aware of Jesus: an expensive Catholic Church with the Altar and Tabernacle being the ultimate focus of all who are there or the expensive Mega church with the Jumbotron and rock concert atmosphere?