To be honest, I got the best results from similar quality stuff, but I used two different whites. The base was a liquid white labelled simply "makeup" That cracked when it dried and I just used Rubie's white "base makeup" greasepaint over top to even out the colour.
This is the result I got:
I forget where I got the random white, but I bought the rubies at value village (a thrift store). You can get it anywhere, really. I think if you bought this kit, it would be smart to pick up the white greasepaint as well to go over top, since the liquid is REALLY streaky. This could definitely improve the quality of the liquid white.
Here's what I mean by the base paint:
http://www.costumeandpropshop.com/detail/RB-18169.html
The get the smoothest white though, I'd use Mehron or Ben Nye makeup, since it's theatre/professional quality. This stuff is a bit more difficult to find. Mostly found in shops specializing in halloween/theatre stuff :/
Also: I think that the kit is worth buying for the wig, it's definitely not bad at all.