Usually, that would be one of the Brother MFC models (especially the Brother factory refurbs).
However, probably due to the semiconductor shortages, they are recently either pretty much out of stock everywhere or, when in stock, have significantly jacked up prices. As a result, you picked a pretty bad time to need to begin shopping for a cheap multifunction machine.
You might check your local Walmart/Best Buy/Target to see what they have on the shelves that haven't yet been sold.
I think Best Buy and Office Depot still have the MFC-2710DW in stock which can be configured to scan direct to PDF for around $200. It has duplex printing as well as wireless networking, but doesn't have a fax function. Brother toners are expensive, but you can buy toner online to do your own refills (YMMV as to quality). If you need fax capabilities, it costs $250 for the MFC-2750DW which is otherwise identical to the MFC-2710DW. Last time I checked, Tigerdirect (and maybe Best Buy) still had them in stock at this price.