If you are getting the 20 gal, u might as well get the 25 gal. Its like only marginally more, and 2 inch taller, same width.
The two inch just saves boil overs.
"Megapots" are manufactured in china and their generic name is sps-XXX(where XXX is number of QTS.(25 gal is sps-100, 20 gal is sps-80 etc). They are widely distributed across the world to cooking stores. Northern brewer adds the weldless fitting and calls it a megapot. If you dont want a weldless fitting, I would go with a regular cooking equipment distributor. Search for sps-100 stainless on google. Here is the best price I found after 10 seconds of searching, but a better price probably exists. http://www.peoplesrestaurantequipco....art-stock-pot/
I bought my sps-100 locally here in london ontario canada for 183 plus tax at Storey Auctions. They gave me a sweet deal!
These pots are amazing pots, which ever you choose im sure you wont be disappointed.