Where could I find a transparent frying pan?
Just search on www.ebay.com for "Pyrex Flameware" and you will find things like :
It is highly unlikely that you will find a new one. The reason is that the formula r for Pyrex before 1940 was way more resistant to thermal shock , but also more expensive. The current formula is more resistant to mechanical shocks but can not take rapid cooling (like adding cold liquid in a hot pan when you are making a ragu) without shattering.
I have no info on the advantages of a glass pan except the "cool factor"
Hope this info helps.
Corning made a Visions pan - I had a set and used it for years. You might find them on eBay or at a garage sale. I didn't really like it as a pan - took a long time to heat up and then stayed hot, thus making a gas stove into an electric and making an electric even less responsive. It's not completely clear, it's kind of brownish.