I personally would love to give this a try.
As for price, I would prefer to do it myself. Practice on some scrap glass ( i have a ton out back of my shed) and from there move up to usable pieces. I know it will not be as perfect, and it is only a lid so perfection is not key. But 120$ for something that they will probably be made in 5 minutes or less by a professional is a little too much of a mark up for me to accept (even if it took 30 minutes to cut the one piece, that is still 240$ an hour minus supplies). Cost me the price of a glass cutter and learn a very useful skill. Hell, I will only charge you $80 Poseidon, maybe use in store credit at your place lol.
I went to the glass places here in the past and asked for items such as glass panels and acrylic sheets, however, they wanted 3times the price from home hardware, same company, same sheet, same dimensions.