1st - I would bet that "Shot Peened" is really 'Shot Cleaned'
They aren't focusing the peening on the stress areas of the block to releave it - they are bombarding it with shot to clean and de-grease it ...
Don't confuse it for making the block any stronger or better than a non-peened block in this case
Those costs seems in line for a preped BBC block with no core.
But ... what are your plans for this engine?
What are the goals for the build - Torque, HP, Induction, RPM range(s), trans type, comeptition or strickly street use ... ???
Those questions answered would make up my mind on what level of prep I would recommend for a given build.
For a typical street-performance mild HP range engine, I don't see the value of doing lots of re-machining of the factory spec. work.
A slight 'line-hone' to true the unit is fine in most cases, but anything more is not warranted for most mild builds and actually, in my experience, tends to induce as many if not more issues than leaving it the way it was ...
If the block really needs this much work, find another block