There are lots of beautiful cups for less than $100 US. I've paid more than that for a handful of cups, and most of the rest were quite a bit cheaper, in the range of $20-60, from artisans who participate in TeaChat, some from eBay, some from non-TC-potters on Etsy. Most of these have also been tea cups rather than tea bowls, so size matters. It's harder to get a really wonderful pot for under $100, but it can be done if you're willing to be patient.
What sort of teaware are you looking for? Large tea bowls? Small pots? All glazed for use with many types of teas? Unglazed for a limited variety?
One specific suggestion for Japanese teawares: this eBay seller
deals in used teawares, a wide variety of sizes, styles, and prices.