I use a vacuum frame but in the past used 1/4" plate glass with no problem. Yes the 300W lamps are expensive. I use the 45watt reflector lamps at about 12 seconds for most proofs from pyrocat negatives. Some of my ABC negatives, that are technically overdeveloped, require the 300w lamp. For other printing I have a 1000 watt HID installed, you certainly won't need that for AZO.