The last time I went to Atlanta (2006) they gave each team 5 Championship posters, though I have no idea if they still do that though.
What might be neater is to print your own posters. Staples does it for a pretty penny, (like $40 for a typical poster size) but
Walmart does it for a a little over $20. Pick your favorite robot photo (or team photo), slap some text on there, upload it and you are good to go!
You can also print it at home and use a
free service online to make it so you can print it out and tape the pages together, and it does look good from a distance, but I'd splurge and have Wally World print it out for you.