many repair people refuse to work on instruments of the walmart variety, due to the extreme inferiority of construction and often weird, non standard parts used.
New wooden clarinets allegedly require much more care than older wooden or any plastic clarinet, and you have to be more careful with them- something about breaking them in so the wood doesnt crack, among other things. i can't tell you details, never having had a new wooden clarinet, but it's good to keep in mind.

i figured there would be a downside to them.. but walmart usually makes good/cheap stuff..

Cheap, yes. Good, not so much...

Yes, you shouldn't buy the departments store clarinets.
My friend bought one in 6th grade, and 4 or 5 months later all of the corks fell off, which was surprising because she greased them regularly.

One person said Yamahas are sometimes ranked with Buffets...

Well I have both.

Although my Yamaha is plastic and the Buffet is wood the Buffet sounds SOO MUCH BETTER!

it would of course depend what model yamaha and buffet you're comparing. since the yamaha is plastic and the buffet wood, it's no great suprise that your buffet sounds better.

Just wanted to let everyone know that I purchased a Buffet Clarinet, online for $504. It looks and sounds great. Its made of plastic so my daughter shouldn't have to worry about it drying out and cracking.