I want it to be something I could ride, but I wouldn't plan on riding it while at the course. Just to and from courses under 10 miles from my house, on days when I'm in the mood.
I did this. I took my old mountain bike and modified it for getting around town. I put on road tires, put on a cushier saddle, put on a rack on back, added two panniers and lights on the front & back. I also bought a device that teathers my dog to the seat post, so she can accompany me and get some exercise too. I even bought a cup holder for my handle bars, for my coffee.
When I started playing disc golf, I began biking to my home course, which is quite close. I don't do it all the time because, while being close, it's also quite hilly. But I do it when I feel like I could use some good cardio. And it's a great way to warm up your body before playing. I always get a nice blast of endorphins as I dismount after riding up the hill to the course and begin getting ready to play some golf.
To rig up my disc golf bag (Innova Comp w/straps) I bought a nifty webbed bungy thing that came with hooks so I could mount my bag across the rack in back. It works great. Whatever extra gear I need to bring, I just stash it in the panniers. The added weight does make for a more strenuous ride up the hills, but sometimes that's cool. I wanna say that I spent ~ $150 on all the stuff for these modifications to my bike.
A while ago I also bought a two-wheeled wagon/trailer from Amazon for this bike because I was feeling ambitious and wanted to be able to haul more stuff like groceries, etc. The trailer was only $50 and it works quite well - it's easy to attach and detach. But the weight of the trailer & the added payload make for an even more strenuous workout going up hills, and (surprise) I don't use it a lot. I think I took this trailer to my home course once or twice but I seem to remember not needing the extra room. Maybe if I was hauling my bag of putters too, it would make sense.
Next time I set up my bike for a trip to the course, I'll take a pic & post it in this thread. But I can't recommend enough biking to your course. It always makes me feel good to do it.