I was an AWE64 owner, and late to the hardware MIDI game. I had friends with superior sounding GUS and Roland gear, but I was still fond of my "cheap and nasty" AWE64 at the time. It certainly made Doom sound pretty cool.
So what's the cheapest way to do this? Surely there's a better option than old stock shipped from Japan?
Even as someone who has enough gear to put together a retro gaming PC with genuine AWE64, I find myself using Timidity++ today instead:
http://timidity.sourceforge.net/Easy enough to use either as a standalone player or a plugin for DOSBox, SCUMMVM, etc. You can load different soundfonts if you like, and virtually try out different MIDI systems.
Comments above apply - real hardware is "more authentic" (nobody on these forums needs that explained to them, surely). But playing old PC DOS games on my much more modern, but still PC laptop is good enough for me, at least, in replicating the memories of yesteryear for that particular platform.