Air Captain Harley Quinn

Now that I can finally start threads here, I thought I'd post a few questions pertaining to a costume idea I've been kicking around.

Combining my love of Harley and the movie Sky Captain and the World of Tomorrow, I thought it'd be kind of neat to combine the two for a steampunkish/sky captain take on the character. Of course I know that steampunk is very much a YMMV kind of thing and something people either love or hate and I'd really like the costume to be something people feel the former about and not the latter so thought I'd ask some questions:

1) In regards to steampunk, what do you guys think is over done as far as props, costume embellishments, etc . And on the flip side of the coin, what do you find to be something you like to see when it comes to this kind of thing. What comes across as being 'quintessential steampunk' to you?

2) While I will be purchasing the majority of this costume and altering as needed to fit the way I'm seeing this I might try to make some of the smaller pieces like a bomber's cap (assuming I don't just embellish a top hat although I might do both if I can get a top hat for cheap). What kind of material would fit the theme/period and where can it be found on the cheap?

Thanks in advance for any answers and/or advice. :cool
Ah! Thanks for pointing me in the right direction Bak. I will definitely give those images a looking through and see what leaps out at me for inspiration. :)