I have the Brother HL-L3270CDW, which prints in color. Ran me about $300 (it’s $270 directly from Brother now) plus the cost of the high yield toner cartridges I bought with it, but you can probably get away with the included toner for a while - with my B&W Brother the included toner lasted me over a year. It says the starters are supposed to last 1000 pages and the high yield 2300, but I’m pretty sure those numbers are very low based on my own usage estimates. I definitely went through more than two 500 page packs of paper in that first year.

It doesn’t have a built-in scanner but it does have:

• wireless and ethernet connectivity, plus support for AirPrint, cloud printing, etc
• direct USB connectivity (though I’ve never used it)
• duplex printing (not for A4 apparently)
• a 150 or so sheet capacity tray (advertised 250) that can handle letter, legal, A4, and anything smaller all the way down to 3” x 4.57”

It says it doesn’t support printing card stock but I’ve printed small amounts (30 or so sheets) at a time, largely without issues. That said, the only times I’ve had the printer jam, I was printing card stock, so maybe there’s some truth to that recommendation.

I haven’t used third party toner but my understanding is that as long as it’s good quality the printer will work fine. It doesn’t force you to only use first party toner.

The color quality has been good enough for my purposes - substantially better than the consumer inkjet printers I used like 20 years ago, but worse than current inkjets. That said, if photo quality color is the main thing your parents print and they print regularly, my recommendation - based on research, not personal experience - is an Epson EcoTank. From their site the entry-level model (the ET-2800) is $200 and comes with about 3k pages worth of ink (and replacement ink bottles have even more capacity). Other commenters have covered it in depth.