ARM processors are not sold separately (in every sense of the word).
ARM holdings, the company that owns the IP for all ARM processors, licences the designs out to companies for a fee. The companies with a licence can then put the various processors into chips, usually designed-in to a system-on-chip which will have various peripherals, buses, interconnects specific for the application. The usual arrangement is to have an entire chip made specific for that application, which means you can buy in quantities of >100,000.
The ARM cpu core inside BCM2835 is the ARM1176JZF-S. As another example, I have a DNS-320L at home which has a Marvell Kirkwood SoC inside. That chip has 2 DMA engines with XOR capability (for hardware RAID), 2 SATA 3GBPS interfaces, a DDR2 controller, a basic i2c and GPIO block, 1-port USB2.0 (EHCI) interface and an onboard gigabit ethernet interface. The CPU itself is a fairly weedy (modified) ARMv5TE.This is because the SoC was specifically designed as a NAS chip.
Rockets are loud.