I don't think there's anything wrong with starting in a shopping mall or a garage, but you shouldn't want to stay there. Applause for the priest whose church is already drawing up plans for an appropriate but modest chapel.
Case in point: the Catholic church in my parents' home town is a mission church with a visiting priest from the nearest big city (well, big city for coastal GA anyhow). It's no bigger than a minute, but it LOOKS like a church.
Agreed. I've been a member of two churches (one PECUSA, one APCK) who started from nothing and eventually put up their buildings. It's not easy, but there is little to match the day you burn the mortgage and consecrate the building (as we did last year).
On the other hand, there is a risk with building too small and too soon. It can actually inhibit the ultimate growth of the congregation.