Do you mind sharing cost, or how much it was to cut to your shape? Ask them if they have "PolyCarbonate" specifically. The plastic place locally told me that should not warp, but "acrylic" will. It comes in both clear and white - so clear would work for you too. I think that may be cheaper than glass but cannot say given I don't know how much the difference is. Food for thought...if you plan to keep the tank for awhile, and you like the look of glass better and it care enough about it's look and function, you may be better off going with glass. I know these things definitely can be costly, especially when you're pulling together a new tank and all these expenses. Sometimes it makes more sense to get exactly what you want, and avoid spending more later. But you may be happy with Poly too. Keep us posted...