I was wondering if you all have some suggestions on good, inexpensive data modeling software tools available on the market right now?  One of my clients is looking for an upgrade to visio that provides the ability to capture:  - cardinality  - foreign or primary keys  - descriptions of entity objects

We have been using erwin Data Modeler (https://www.gartner.com/reviews/market/data-and-analytics/vendor/quest/product/erwin-data-modeler) as part of our development life cycle (application and analytics), using it's outputs into a change database tool.
I would not put it in the "inexpensive" category, but it helps us to keep in track that every table and column created follows our data modelling definitions. So tools just for graphic drawings was not an option.

We wanted a simple EA tool to do modeling for our business and application architecture. We bought dragon1 and it seems it serves the purpose.

Im quite sure that vsio can be used for data modelling (How To Use Visio for Data Modeling | Advisicon Blog)- including primary keys and cardinality.  Drawio also does the job.

I’m a fan of Lucid Chart over Visio. You can check it out for free to validate that it would work for you. It’s a general diagramming tool so you can use it for other purposes.