I only know about the Open Seasons #'s 1-4 comic book series (should be available on ebay). But in his earlier years in those, he's seen in a dark grey flightsuit. Only reason I know is because we own them and I'm almost finished converting what was my Ep2 Jango into an Open Seasons #3 Jango.:confused
I actually have a pair of Red Kapp postman blue coveralls in my extra's bin. It's been washed about a half dozen times so it's got a good faded look to it, and I would have to say that in an already-made coverall it does make a good flightsuit.
When I first got into this I started out the same way you did but eventually ended up making my own flightsuit. If I had to go back and do it over again though, I would have saved myself a lot of time and frustration by purchasing a jumpsuit from Bobamaker or Skygunbro...and it probably would have cost about the same amount of $$$.
Hope that helps too,
Cruzer