Then let that be your mission, for the time being: to build your experience to the point where you feel comfortable taking a cavern course. As for the cost of training, travel and equipment: yes, it can be expensive, no doubt about it. But there are ways to minimize the pain. First off, the cavern course can largely be done with your recreational rig, with a few modifications: your instructor will show you how to tweak your gear so that it's suitable for your environment. So, that's a cost saving right there. When the times comes for you to take the next module or two, which entails investments in double tanks, another regulator, more spools, lights and so on - don't underestimate the benefits of used gear. People upgrade their gear all the time, or periodically need to thin out their dive closets, so you can pick up great gear for considerably less than the recommended retail price. Talk to your cavern instructor, and ask him/her about their views on certain types of equipment. That may give you a better idea of what to look for, when the time comes.
If you decide to go this route, I warn you: it'd addictive. My SO relates how he reached the Grim Reaper sign at Orange Grove as a cavern student, and shone his light past the sign, to the cave beyond. The only thought going through his head was: "Oh, crap. This is going to be so very, very expensive!"