Philips 42" is nicer for the equiv. price
Sanyo does not make bad TVs (see the Legend TV thread), put it that way. Yet according to an established consumer magazine, the brand is prone to have more repairs than the premium brands. It is your call to evaluate the benefit and trade-off at the price Walmart sells. There is one Philips 42" 720p/768p? plasma of similar price. It has lower specifications compared to other premium brand 42" plasma, but if you like to shop at Wal-mart, then you are better off with the Philips. A Philips is a Philips.
If you scope is 50" inch and like to be value-conscious, wait for summer time as the big box retailers will drop prices. I reckon at that time you pay $200~ $300 more for a 50" 720p popular brand than you pay for a Walmart Sanyo 720p 50" right now, then it's quite worth it.