Double Pane Glass

[Kent Harris]

About 2 years ago my landscaper's lawn mower through a rock at our 36"X72" double pane window, shattering it into a million pieces. The replacement cost was $300 installed. The landscaper reimbursed us for the window and also provided the Glass installer. Since I have 11 rental properties I have 3 different maintenance people with different skill sets. All 3 can replace single pane glass. None however know how to replace double pane. Since then the Glass installer has moved on and shut down his business. How do I go about finding an installer that does double pane glass? Typically I pay my maintenance people a base rate of $50 per service call, obviously if it requires more than 1 hour labor I pay them more. Last week a bird struck one of the double pane windows and broke it. The estimate I got was $260 for a 36"X36" window. Has the cost of double pane gone up? How do you go about finding the glass supplier? If a maintenance person can replace a single pane can't they replace a double pane?