From what I've heard, Mike McDole's got the best Pliny clone out there. A quick google search will turn up a recipe, so here's a link to one that should help you out.
BeerTools.com Recipe Library - McDole's Pliny the Elder Clone
On topic: I use a Coleman Xtreme cooler from walmart, 70 quarts (17.5 gallons). I currently brew 5-gallon batches, but wanted something that will allow me to step up in the future. This will do it. At Wal-Mart online I see its for sale for less than $40. I modified mine to use a SS hose, and so far it works great!
Walmart.com: Coleman 70-Quart Xtreme Cooler: Camping
I have no experience using the aformentioned 10 gallon coolers, however my concern would be, if you're brewing 10 gallon batches, and you want to brew bigger beers (with large grain bills), you might not be able to do so bc they're too small. Someone who has used those coolers should confirm or deny my speculation, but that's my 2c. Happy brewing!