How Can I Get The Value Of My Tiffany Lamps Without Paying For An Appraiser?

I received 2 dragon fly lamps and I am curious of their value One is an tall telescoping type with 6 bulbs and all bronze base, The other is a lot smaller with bronze dragonflys of the base the shade rest of three bronze armsThe taller lamp has number eched in the underside of the base with a bid z and a little c brand in felt pen,How Can I Get The Value Of My Tiffany Lamps Without Paying For An Appraiser?