You would probably start by co-locating in multiple data centers, if you rent large amounts of space you can get quite decent deals. You'd have to do this with

You would probably start by co-locating in multiple data centers, if you rent large amounts of space you can get quite decent deals. You'd have to do this with the best DCs you could find, however. Once you had enough demand to merit your own data centers, then would go ahead and build them. Thats what most VPSs do.