In hindsight, the commercial wigs really weren't much help – the knotting was not great for the most part, and all but one of them were knotted on stiff, scratchy monofilament mesh, not lace at all.
As a result I have a small collection of mediocre commercial wigs that are just sitting on a shelf in my office. I decided, rather than let them go to waste, that I would re-front them using decent lace and finer knotting.
I just finished the first one. The main body of the wig is good, and even the knotting wasn't terrible, it's just that the scratchy monofilament (aka 'German' lace) was very uncomfortable. Also the shape of the hairline was very round and unnatural.
I have redone the entire lace section using only single (2-way) knotting, and I think the final result is much more natural. This is high temperature synthetic hair, so it probably wouldn't work as a hair-replacement wig, but I think it would make an excellent theatre or opera wig or even a fun fashion wig.
As a side note, I have the wig on a cheap plastic mannequin head that I bought to help when I'm working on hairlines. I find the eyes really disturbing, which is why I have it wearing sunglasses... :P