FIPS 140-2 Security Level 2 does not require any form of security measure to prevent extraction of secrets. It simply requires tamper evidence, that is, it should be possible to notice that such attack took place by looking (for instance) at some seal on the device or at a log file.
To answer your question, extracting a secret may therefore take 0 seconds and 0 dollars.
Only Security Levels 3 states that the cryptographic module must respond to attacks, even though the requirements are not phrased in terms of attack cost, but rather of guidelines the module must follow. For instance, it says that the circuitry should be covered in hard epoxy, but not exactly how, so a manufacturer could also choose a substance a hairdryer can easily melt.
A good source of material to look at is Ross Anderson's group at the University of Cambridge, and more in particular the work of Mike Bond.