Somehow, the good table tennis shoes are a bit more expensive than they should be. The inexpensive ones are not as good.
I use indoor soccer shoes. The specs on indoor soccer shoes are very similar to table tennis shoes. Very thin sole. There is really no heel (heel of foot is not higher than ball of foot). Wide sole, low to the ground for lateral movement.
Part of why you may want specific shoes for table tennis would be if your club has an indoor court surface. Then, indoor court shoes would be really helpful. Also, the low to the ground profile actually helps keep you from turning your ankle. A shoe designed, say, for tennis, where you are higher away from the ground is not as good for the movements in table tennis.
Indoor Volley Ball Shoes have pretty similar specs and an indoor court sole as well.
An indoor court sole is made out of gum rubber. If you wore it outdoors it would wear out very quickly. But on indoor courts it gives you the correct amount of traction you need without too much grab, so you get more torque and your knees are a little safer.
All in all, I would say a reasonably priced indoor volley ball or indoor soccer shoe would be worth it. Or, if money is no option the top of the line Butterfly shoes, Mizuno TT shoes, or Asics TT shoes, all are GREAT. The top of the line Butterfly shoes are actually made by Asics anyway.
Mizuno are supposed to be the best ones though. And if you look, so many top players use them. I think the whole Chinese National Team uses them, even the guys sponsored by Butterfly.