The Kenmore 50 Gallon gas water heater comes with a 12 year warranty on the tank. The model number 33115 is sold for just under $700 and can be delivered for an additional $70 from Sears. This tank seemed to get some pretty decent reviews from the users on the sears website.
Of the negative reviews there were a few complaints that Sears was not able to get out to warranty the water heater for over 3 weeks. Not exactly a reasonable time frame when you are without hot water.