If you do not pay, the incident will likely be reported by the former employer, charges will likely be filed, and you will likely end up paying restitution to resolve the charges anyway. Even though the value of the property is questionable and low, you could be looking at a felony charge since you were an employee. I would suggest continuing with your agreement with the former employer to avoid charges. If you are having difficulty paying and can justify your challenge to the $780 amount you might try renegotiating the restitution amount, but I would not walk away from the deal all together.
These comments, based on limited information, are not intended as legal advice and are not to be construed as creating an attorney-client relationship. For legal advice consult with an attorney to get a thorough review of the charges.
I agree with Mr. White. You made a few mistakes here. First, Judges do not like the "I was pressured" argument. You may have felt that way, but if that happens, you need to leave the room, not make admissions that you now say are lies. Because you came up with what you say, you stole, but only to get rid of them, a court would not find this credible now. If ever in this situation again, walk away and go speak to an attorney...do make criminal admissions for acts you did not do.
Are you still working for the store? Did they make any attempt to press charges?