I am a flat rate (Piece-rate) mechanic in Florida at an independent shop (Non-dealer) that is wondering a few things. First, am I eligible for overtime pay ?
Let's use the following simple example below to show how I am currently compensated.

In this example lets say I make $10.00 per piece rate hourly.

I do 50 brakes jobs during my work week for 1 flat rate hour each which equals = $500 (50 x $10.00)

And lets say that I was at work a total of 60 hours that week

My hourly rate would be 8.33 an hour, because my total flat rate pay is divided by my clock hours ( $500 / 60 clock Hours ) = $8.33 hourly

I've been told I should be getting paid for 20 hr of overtime at my hourly breakdown rate. which would make my pay

$ 8.33 x 40 Regular Hours = 333.20 plus overtime which is 12.5 x 20 Overtime Hours = $ 250
for a total check of $583.20

And two I heard there's a law that states technicians that have to supply their own tools must be paid at a rate of at least twice the rate of minimum wage in that state. I'd really like some help here, I'm getting different answers and would like to know what I'm eligible for if anything.

The law you reference about tools is a California law. To my knowledge, Florida has no such similar law. Florida has hardly ANY wage and hour laws of its own.

You are entitled to overtime pay, but your calculation is not quite correct. The "job rate" total is considered by the FLSA to cover the straight-time portion of all hours worked during the workweek. Therefore, the overtime premium portion (half rate) is all that is due under the FLSA.
http://www.dol.gov/dol/allcfr/ESA/Title_29/Part_778/29CFR778.112.htm

I guess I'm a little slow but I don't understand how I'm supposed to get paid for overtime then, I'm guessing if I averaged the $ 8.33 an hour half of that is $4.16. So I'd be owed 20 Hours at $4.16 an hour for overtime compensation ?

That's correct. It's all that the FLSA requires.

Thanks for clearing things up for me. I appreciate the help tremendously :)

The worker probably would not be authorized any overtime under the 7i exception...

For those who do not know the jargon, the "7i exception" is refering to the part of the FLSA law handling the Retail/Service Establishment exception, which may indeed be applicable in this case.

http://www.dol.gov/esa/whd/regs/compliance/whdfs20.pdf

FLSA law, section 7:
(i) No employer shall be deemed to have violated subsection (a) by employing any employee of a retail or service establishment for a workweek in excess of the applicable workweek specified therein, if (1) the regular rate of pay of such employee is in excess of one and one-half times the minimum hourly rate applicable to him under section 6, and (2) more than half his compensation for a representative period (not less than one month) represents commissions on goods or services. In determining the proportion of compensation representing commission, all earnings resulting from the application of a bona fide commission rate shall be deemed commissions on goods or services without regard to whether the computed commissions exceed the draw or guarantee.