Depends on who you talk to. I've published a handful of plugs, some with original graphics and some with rehashed Nova graphics. I've been doing a lot of work for the Firefly TC, and I have a few irons in the fire right now that might see the light of day at some point, including a plug that adds the Defiant-class warship to the game. I've got it more or less done, actually, but I still have final balancing to do, a little graphics work with the interface, and some play-testing to do with it.
Plug-making sounds pretty intense, and it can be, especially at first, or if you have no experience with computer programming. However, the resource editors that are available are also quite easy to use, extremely helpful, and have exceedingly good help built into them. For example, in EVNEW, hovering over any resource flag or field gives you a description of what the resource flag does, and even some helpful tips and tricks with the resource flags. If you download the resource editor appropriate for your platform (Mission Computer for Mac, EVNEW for Windows,) and the Nova Bible, which can be obtained on the Add-ons page, you should be in pretty good shape. The bible can seem pretty technical at first, but if you play with a few of the resources, you can probably pick it up fairly quickly.
I'd offer to help you out with this personally, but I have quite literally no time these days. As I'm writing this, I'm on my prep period from teaching, and should be grading the dozen or so outstanding assignments that I have to have into the system by Friday. Taking resources out of one plug and making your own out of it is a good opportunity for you to learn how to do plug-making, and I think you'll find the process educational and rewarding.