Have you looked on Etsy? I love Etsy for AB gear!
Here is one that is an 8oz plastic baby bottle but with a big adult-sized nipple:
https://www.etsy.com/listing/523744692
There are these 14oz, 24oz, and 40oz BPA-free plastic bottle converts that are designed:
https://www.etsy.com/listing/504454428/
These AB "My Bottle" versions are sold under many different stores and may be okay for something quick and affordable:
https://www.etsy.com/listing/481029362/
I like glass bottles so these 22oz ones with the silicone sleeves kind of catch my eye (these are probably my favorite ones from this list that I found but, again, mostly because I really fancy glass):
https://www.etsy.com/listing/506195185/ &
https://www.etsy.com/listing/502549661/
I guess these sorts are kind of popular. This one is glass but has a livestock feeding nipple that is longer (which I don't personally like because it isn't realistic enough for me but maybe it's your thing):
https://www.etsy.com/listing/498219111/
Wearing Clouds sells their versions here:
http://www.wearingclouds.com/product/ad ... by-bottle/
Cuddlz version:
http://www.cuddlz.com/cuddlz-240ml-bott ... e-or-pink/
Baby Pants versions have a variety of prints (even Mickey Mouse) and colours:
http://www.baby-pants.com/nursing.php
(A lot of these you can buy on Amazon too if you feel more comfortable:
)
Rearz sells their versions here:
(Printed with handles):
http://rearz.ca/adult-printed-baby-bottle/
(Zoo print):
http://rearz.ca/baby-zoo-specialty-feeding-bottle/
(Better grip):
http://rearz.ca/easy-grip-bottle-w-specialty-nipple/
(Regular):
http://rearz.ca/specialty-feeding-bottle/
Rearz also sells a plastic 9oz feeding bottle with handles:
http://rearz.ca/feeding-bottle-spill-proof/
ABDLFactory sells NUK branded adult baby bottles too
Small size:
http://abdlfactory.com/glass-baby-bottl ... for-adults
Large size:
http://abdlfactory.com/other-ab-dl-prod ... mmie-240ml
AwwSoCute sells what they call Boobie Bottles that are suppose to mimic breastfeeding with how it feels against your mouth and is silicone so soft and squeezable:
https://www.awwsocute.com/bottles
Recently I found a mason jar that had been converted to an adult baby bottle. It's kind of cute if you're into rustic things or want a larger size (16oz) without being too too large, and the weight of the glass might feel nice in your hands:
https://www.etsy.com/listing/552400617/
Sippy cup versions of the mason jar baby bottle:
https://www.etsy.com/listing/554009575/
https://www.etsy.com/listing/237180361/
https://www.etsy.com/listing/466313947/
Anyway...here, check them out!
https://www.etsy.com/search?q=AB%20bottle