My cheap method:
Buy two sheets of grey 16x20 acid-free matte board. After rinsing your fiber print for at least an hour or more, squeegee it on glass (carefully, image side up, make sure glass is clean). Using wooden clips, hang it by two corners on fishing line in a warm area (I do mine in the kitchen over a gas stove, not on) so that the surface water on the back of the print drips off. Before ANY part of the print gets totally dry, take the print and lay it between the 16x20 matteboards. Make sure you use the grey side of the matteboard against the front and back of the print; the grey sides will absorb the remaining moisture.
Place the "Print Sandwich" on a flat table. Grab the heaviest and biggest books you have, and stack them tight and evenly on the sandwich. Leave print(s) compressed for 1-3 days. Trim 1" off the edge, and you will have a 15"x19" flat print with very little to absolutely no curl.
As you make more prints in the same darkroom session, simply add another sandwich to the first one, books on top as before.
Complex, but it works and its cheap! No need to buy a print dryer or pay a lab tech to dry them for you. And no, I have had no staining on my prints after using the same 16x20 mattes for at least eight months now. Wash the prints well and long! Note I have not been able to keep a full and untrimmed 16x20 from edge curling, but this method works great on 11x14 and smaller paper, plus as I said above, you can trim 16x20 down to 15x19. With experimentation (and patient waiting) you'll probably come up with a simpler way for yourself without large investment.
If you're pressed for time, then sandwich the print(s) overnight and check the results the next morning. If that doesn't cut it for you, then pay the guy at the lab and pray he does it right with his heat press.
Good luck,
Chris
canonetc