I don't know which banks use brinks, but my whole area is supplied by them. $500 to work with a few times a month isn't bad. Here's your options...
Denominations of coins which some in boxes are:
$25 box of pennies-------I am averaging 18 wheats per box, though most common wheats are valued at $0.03 each, making it just a novelty search.
$100 box of nickels-------I am averaging 1 silver every box or so, but they are heavy and could be tough on your eyes.
$250 Box of dimes--------I am averaging 1 silver every 3 boxes
$500 box of quarters------your odds of finding a silver quarter are very slim
---------------------------------All of the above is avialable at banks without ordering----------------------
$500 box of half dollars- most banks(if not all banks) have to order them for you, some banks charge a fee, some don't. Note: I am on a 10-box half dollar streak with no keepers whatsoever.
(all of these coins are brinks, except for the half dollars, i get a mix of brinks and what i believe may be Garda. (I am 0 for 3 with brinks half dollars, 0 silvers for $1,500 searched).
hope this helps.