What are some of the best under $100 rod blanks?

American Tackle Bushidos and Rainshadow Revelations.  Both series are very good at reasonable prices, and you have to spend a lot more to get better.  I was assuming you were talking about bass blanks, cast and spin.  If you could provide more info on exactly what you are planning we might be able to get more specific.

North Fork Composites seem very nice, particularly when on sale. You may have to wait weeks for the in-house blank manufacturing, however. Have one being built, one on deck and two on order.

3 hours ago, BayouSlide said:

North Fork Composites seem very nice, particularly when on sale. You may have to wait weeks for the in-house blank manufacturing, however. Have one being built, one on deck and two on order.

 

Agreed

 

Allen

I am looking for a casting rod that is around 7 feet and is a medium or medium heavy if that changes anything 

Nope, all mentioned have them.  If buying NFC blanks to build into rods be aware that many of them, unless you get the "mirror finish" option, have ridges that some builders, especially new ones, find troublesome when wrapping the guides.  Amtak and RS are smooth.