Which Vintage CD Player To Use As A Transport?

Is Bulletproof and $100 mutually exclusive?

I had an old Sony DVD player that sound great as a transport, just could not believe that thing sounded as good as it did. but ultimately like all cheap players it died. Splurgitate and spend $350 on a used Cambridge Audio CXC and more than likely save $ in the long run.

Get one with a digital output so a better DAC can be added at some point. Denon has worked well for me, but all can benefit from new drive belts and lube

No, it is not a good idea, based on my experience. I switched from Arcam 192 being used as a transport some time ago and the difference versus Cambridge CXC was enormous, since than I climbed the ladder higher, but this is different story.

Find an old Pioneer Elite and do anything you want with it. They sound great either way and are solid as they come. I have 2 PD65 and gave one to a dear friend years ago and they all still work flawlessly. Before my Marantz player, I used one as a transport into a Mac C50 and the platter was quiet as a mouse. It will be more than 100 bucks, but good god my brother, your front end is super important, and you get what you pay for. Save for a while and buy something in the $500 realm. It will be worth it. Or not. Enjoy the music either way.