Cloud versus buying my own iron

At some point in the next year we're going to reconsider our hosting
environment, currently consisting of several medium-sized servers (2x4
CPUs, 48GB RAM, 12-disk RAID system with 8 in RAID 10 and 2 in RAID 1 for
WAL). We use barman to keep a hot standby and an archive.

The last time we dug into this, we were initially excited, but our
excitement turned to disappointment when we calculated the real costs of
hosted services, and the constraints on performance and customizability.

Due to the nature of our business, we need a system where we can install
plug-ins to Postgres. I expect that alone will limit our choices. In
addition to our Postgres database, we run a fairly ordinary Apache web site.

There is constant chatter in this group about buying servers vs. the
various hosted services. Does anyone have any sort of summary comparison of
the various solutions out there? Or is it just a matter of researching it
myself and maybe doing some benchmarking and price comparisons?

Thanks!
Craig