The main problem with today's printers is they dont have any brains. They depend on Windows to supply most of the CPU power. For serial, you need a printer with a CPU, memory, spooler, and fonts.
Elevmike, if you're thinking of today's printers with USB inputs, serial to USB probably won't work, because you still need Windows drivers (and 2 way communications) to run them. An HP laser with a network input might fly.
There's still 2 dot matrix printers available. Okidata and Epson. For serial, I think Okidata is your only choice. Get it from an office supply, and most likely order the serial input option card.
The other choice is HP lasers. They have options for network, serial, HPIB, and parallel.
Either choice will put you in the $300.00 and up price range.
If you don't mind 40 column and thermal paper, you can find these around for under $100.00.
The other suggestions above are also accurate for POS, Epson, and Okidata.
Another option is to use an HMI with a printer port. The HMI'S are a single board PC, so it's easier to support printers through these.