Make your own bike cup holder using an empty can. Decoupage with images for extra flair.
Flower bicycle cup holder bicycle by RockyMountainHolster on Etsy
Coffee cup holder for a bike - Delta Cycle Grande Beverage Holder
Bicycle Accessories Cup Holder Cruiser by RockyMountainHolster
Vintage Fashion and Lifestyle Cruzy Kuzy Leather Bike Cup Holder Handmade by Hide & Drink
BikeCraft 2012-21 by BikePortland.org, via Flickr
Bike Cup Holder – Java & Thread
Kroozie XL Cup Holder with Foam Insert