I don’t know if any place that will sell you a quality adult sized pacifier for less than $20. Most good ones are $35+. The nipple/teat they use is from an actual medical device and, so, it’s hard to get one of those made with medical-quality material and standards for cheap. Recently, I did run into a shop that’s at least offering different teat styles, which could make a difference regardless of quality, but you’d have to see about their prices and research if they’re at all reputable:
I can tell you that my partners feel strongly that the premium prices are worth it.
We buy ours, and absolutely recommend you do too, from: