"May I use seed of a patented Crape Myrtle to sell?"

Absolutely! Plant patents cover vegetative propagation, not seeds.

"Are there any Red crape myrtles that are not patented?"

Quite a few. Some of the more popular reds, like Whitcomb's selections, are patented, but there are many more that aren't. All together, there are currently 54 patented crape myrtle cultivars. There are hundreds of non-patented crape myrtle cultivars out there.

"Which would be the reddest color?"

I'm not sure you'd find agreement on the answer to that question. Here are some websites that illustrate/describe some of the many crape myrtle cultivars:

Texas A&M Aggie Horticulture's List of Characteristics of Crape Myrtle Cultivars

Clemson University Extension Service's List of Crape Myrtle Cultivars

US National Arboretum's Crapemyrtle Quick Guide Chart

NC Cooperative Extension's List of Lagerstroemia indica Cultivars

A list of patented cultivars can be found at the link below.

Here is a link that might be useful: List of Patented Crape Myrtle Cultivars

Brandon7, thank you so much, you are a life saver. This is great info. DM