Local hardware and craft & hobby stores would be best. In fact a local “dollar store” near where I live actually sells them.

It really depends on the quality of tool you’re looking for.

I’d start with somewhere like Home Depot or Home Hardware.

You can buy an ordinary carbide wheel glass cutting tool for under $5 at almost any hardware store or home center. If you wish to take narrow slices of glass off the sides, then you need either parallel jawed pliers or what are called grozing pliers and most likely you will have to hit a stained glass store although some hardware stores have them.

They look like this
-http://www.Tracysworkshop.com/p-3323-knipex-grozing-pliers.aspx?affiliateid=10050 with one curved and one flat jaw.

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