Thanks fo clarifying that Wook.
I didn't mean to shoot down the idea right off the bat. My concern is that a Dress Blues tunic (like any military dress coat) is a tailored suit usually made of Wool Gabardine. Wool Gabardine looks amazing giving that firm, stiff appearance with sharp, clean lines. It's also terribly expensive and the main reason the coats we've seen are in the $300 to $400 range.
Using a less expensive material might upset the sharp look the tunic requires to appear right. It could end up looking like an ill fitting black blanket. In the end I don't believe there would be a significant savings going with a custom job (having them use the correct materials) as oppossed to using Marlow White- which looks spot on to our needs.
Again if Marlow White is out of just about everyone's price range- then why not revert back to using a USMC tunic?
EDIT- Ok Ive had a glance around that site and found this:
http://www.mooncostumes.com/item/5282
Mixed feelings on this- the overall look is fairly close to what we need. We would need it customized with red trim, and gold buttons. It looks a wee bit on the long side to me though, and I'm unsure if we need the breast pockets or not. Personally I would want them as just about every US military coat has them (they just look sharp and make it easier to place your ribbons in the right spot too

).
Anyway- the price listed is for a set of jacket and pants. The jacket alone would probably be in the $100 range, but with the customizations needed (and the starting quote of $200-$350 for custom work) will it really be a huge difference in cost?
Like I said- mixed feelings.