As for cutters … lots of options, but very few locally available (AFAIK).
MSC is a good source - but these are going to be professional quality cutters.
Grainger can get a wide selection of more common end mills and you can pick up at their store to avoid shipping cost. Can take several days (or more) if you need something exotic.
You can go to CDC Products in Richardson for various cutters but he’s essentially a miscellaneous shop so you may or may not find what you want there. Sometimes you get lucky - other times not (but if you go to CDC, and lots of us do … he’s closed Sun & Mon and does not take credit cards - only cash/check).
If you need small cutters, and you’re not machining steel - try Drill Bits Unlimited. They frequently also have gently used end mills or drill bits at incredible prices.
So I did find inadvertently another source locally WM Hurst in Grand Prairie a year ago so. I have not checked them out so I dont know what they stock locally or if they sell to the general public. https://wmhurst.com
Another is Technitool in Garland, No dealings with them at all, so I dont fully know their offerings Products - Techni-Tool, Inc.