I have bought from Northwest Territorial mint in the past; the nice thing about them is that if you buy in large quantities the shipping and insurance is free which is nice for big orders; the down side is it can take them 6 to 8 weeks or sometimes even longer to fill your order.
I got an interesting email from them yesterday about converting your large bars into denominational silver and their prices:
Total Conversion Outlay:
Over 5,000 oz:
$0.85/oz
Over 1,000 oz: $0.90/oz
Over 500 oz: $1.00/oz
Over 100 oz: $1.10/oz
Less than 50oz: $1.30/oz
Prices are a ‘per ounce’ amount over spot. You may combine bars or rounds in any combination for the ounce total in the transaction.
Shipping & Handling:
Continental U.S.*
Free
Alaska & Hawaii 10¢ per ounce
Canada 30¢ per ounce
Over 500 ounces: 20¢ per ounce
*No Added Fees, No Hidden Charges And No Extra Costs
**********
I guess it could get pretty hefty if you had to pay $900 to convert your 1,000 ounce bar into 1,000 ounce denominational.
However, sometimes you can get large bars for below spot. I had a dealer offer me a 1,000 ounce bar for below spot a year and a half ago but didn't buy it because of the convertibility issue.