Online screen printing is a great, affordable option that allows you the freedom to create whatever you choose.
You can even find iron-on paper so you can create your own mini screen printing shop in your living room or office.
Most screen printing shops will waive the requirement to order in bulk if you're willing to pay slightly more for the one-time print.
You can visit a local screen-printing shop, or make your own with fabric paint, printable fabric transfers, or markers.
For instance, if screen-printing t-shirts for each guest isn't in your budget, maybe it would be possible to buy everyone a white t-shirt for tie-dyeing.