Eigenvector wrote:
I'm calling around for some sort of quotes to replace my failing circuit
breaker box and so far I've only received one estimate.

The price they quoted was about $2500 bucks roughly or $91/hour for their
work - including permit and inspection. No other electricians want to
release their hourly rate nor provide estimates. I'm not bitter about it,
just interested in how much money I'll have to secure to do this.

So if you had to guess, what would it cost to replace a non-grounded circuit
breaker with a grounded circuit breaker IF I SUPPLIED THE BREAKERS AND THE
PANEL.

$2500.00 sounds to me like they should be holding a gun to your head.
Not knowing particulars I would ball park around 300 to 500 or less
being your furnishing the materials.