@gordoa40 You would be surprised that the list I made covers most of your cnc routing needs.
The reason for an up cut bit is you are not worried about material tear out. Materials such as plastics, and soft metals need as much material removed as possible. If don’t remove aluminum and over heat the bit. You get chip welding which is bad. It will break you bit. Plastics need as much material removed from the cut as possible also. If the material is left in the cut it can reweld itself in the kerf from the residual heat.
A down cut bit is great for pocket cuts into plywood. Plywood has opposing grains and will tear out if you use an up cut bit. The down cut bit is forcing the grain down into the plywood. A down cut bit has a con. If you cut through a sheet of plywood the bottom can have tear out since you are forcing the grain out of the bottom of the cut.
A compression bit is the best of both worlds in terms of plywood. The lower geometry is a up cut bit. The remainder of the cutting flutes is a down cut bit. You have to set your initial pass to be deeper than the up cut bit height. A 1/4" compression bit has 1/4" of up cut geometry and the remainder is a down cut bit. If you don’t account for that you will lots of tear out and a lot sanding to do.
I would look for Amana bits they are are high quality. You can start experimenting with lesser quality bits after you get the hang of cnc routing. I would recommend you get an 1/8", 1/4" bit diameter for most of your general purpose cutting. A 3/8" or 1/2" will give you more cutting ability to include rigidity, but cost more and might not serve your purpose right now.
Locally I would check out Sparktech in Round Rock or Dixie Tool Crib in south Austin.