You may want to try an lightweight overnight tour soon to check see how you like it. You can really get stuff on a budget if you can plan on warm weather. I did one last weekend here in Socal where I can count on no rain and temps staying above 55 F.

I took:

Backpacking hammock from Campmor: $20
Car windshield screen pad for insulation, from dollar store: $1
Fleece sleeping bag: $10
Emergency mylar blanket for a ground cloth (unused): $3
Pop can aluminum alcohol stove cookset with pot: $10 (optional)
shorts, tee shirt, socks, thermal tee-shirt: already had them

All this and some other optional goodies fit into a $9 book backpack from Walmart, plus a $4 homemade handlebar bag, and strapped atop an inexpensive rear rack. The pack could do double duty if you ever wanted to do some day hiking.

Just want to point out that you could do this cheap setup and roll out on any bike to get a taste of touring; no need to buy hundreds of dollars of gear and build up a bomb-proof expedition bike first.

I'd have to say my hammock is my favorite essential piece of gear, with the alcohol stoves coming in second.

A seven-inch tablet is my favorite luxury, I have one with a microSD slot so I can view the videos from my action camera and upload them, plus all its internet and entertainment value (movies and ebooks), plus the offline maps I've loaded (OSMand and Maps with Me).