Here are some of the things to consider before making this a full time job.
I may be wrong here but I ran a few numbers from this past year's averages. To make $200 a day in my area...:
1) You will get an average of 3 coins per box. This is "my average" and they are two 40% and one 90% per box. Plug in more or less and it will change everything

.
2) Assume you want 150 coins. Thus 150 coins / 3 coins per box = 50 boxes a day
3) 50 Boxes / 15 minutes a box to search = 16.666 hours per day
4) Assumes you have a bank which accepts $1000 bags of coins for returns. It is included in the search time! Good luck finding a bank to accept twenty five bags a week without the "F Word" coming up soon.
5) Assumes silver prices remain stable.
(100 40% x $2 return per coin + 50 90% x $5) = $450
6) ($450 - $75 cost coins) = $375
7) $375 - $50 expenses = $325
8) $325 x .33 (Taxes. You are self employed and this is a business! Keep those receipts

) = $107.25
9) $325 - $107.25 = $217.75 per day
10) Not to be a pessimist but as a full time business it won't last long.
11) As a hobby you can have a good time and you might get lucky and have a dream box or two or get a customer roll bonanza. I had one that was really shot up my averages!
Maine_Jim