Yes! Your rolling stock can have custom lettering. For years, I would envy the modelers in magazine articles who had custom-lettered cars. "That fellow sure has more artistic talent than I do," I'd think. But no more. Happily, the availability of personal computers and graphics software means that anyone can turn out high-quality artwork with little effort.
This Virginian hopper is a good example. I created the artwork using Adobe Illustrator, and many photos for reference. The work, while time-consuming, wasn't difficult. I estimate that I spent about 20-25 hours on the hopper artwork, spread over several months (whenever I felt like it).
I urge you to take a crack at it too. Begin with something simple and move into the more complex stuff as your skills improve. Don't get hung up on making perfect artwork (the goal is perfect lettering) - use whatever tools your graphics program provides.
For example, the round VGN herald was a real challange at first. Then I discovered that I could add shapes above the desired artwork to mask off unwanted lines. The herald consists of the VGN letter shapes below a stack of black circles and white circles, to trim the ends of the letters to match the herald's circular outline.
Once your artwork is complete, check the ads in modeling magazines for custom decal printers. You can order decals in small quantities (say, 25 cars) at a cost of about $1.25 per car; the price per car goes down as the quantity goes up.
If you have many cars, consider having them printed instead buying (and applying!) decals. I had 162 hoppers pad-printed at a cost of about $1.40 apiece (including the one-time cost of making a negative and printing plate; subsequent orders would be less per car). Road numbers were omitted, and will be applied individually using dry-transfer sheets.
So give it a shot! You may be surprised to discover how little effort is involved - and how great the results will be.