i’m in the business and i can tell you that buying a good sheitel for everyday and a less good one for shabbos is a much better investment than the other way around. because you use an everyday wig much more, it’s much more likely to get worn out faster than the shabbos one.
that having been said, i can’t help you for america, but if anyone’s reading this is in israel,there’s an annual sheitel sale benefitting hachnosas kallah (i don’t know which fund) that sells custom sheitels, very nice natural but not custom ones, and also gmach sheitels for dirt cheap (obviously this term is relative to the wig – the gmach sheitels are between 100 and 400 shekel depending on condition, the nice human hair ones are between 100 and 400 dollars, and the custom ones are 400 and up, but under 1000 i think – these are approximations; i’m remembering from last year). the next one should be”H be in cheshvan 5771.