How much does pin count, die size, transistor count and transistors size effect the CPU price. How many transistors do registers typically take up, and how many transistors are saved by using a RISC architecture over a CISC architecture?
Respectively:
pin count: a fair amount
die size: a whole lot
transistor count: not so much thanks to moore's law
transistor size: a huge amount, in an extremely nonlinear manner
A register will take somewhere roughly around 10 transistors per bit, very loosely
It's really hard to compare RISC to CISC in a meaningful way. What RISC got us, in the 1990s, was that it made it easy to design instruction set architectures that supported 32 registers. But variable-length instruction encoding greatly eases memory pressure. And regardless, most historically-RISC designs now look awfully CISC-like, because of grafting on SIMD and other data-processing instructions.
I'll assume you're talking about history, and not the cheapo Allwinner A10s you can get for 7 bucks.