Why won't we do custom orders?
I was warned about custom orders by Joe Covais, who used to own New Columbia. When he closed shop in 1992(?) I bought his patterns. He was in business for about 15 years, and he tried to give me as much advice as possible. We talked at length and he was very clear on one point. One that contributed to the failure of his company.
Custom orders.
They are a loser.
Every time.

Basically, it goes like this:
You make a guy a set of special order trousers, send them out, and;
"They're too small. I want a refund".
"They measure exactly as you ordered."
"Too small. Don't want'em. I changed my mind, changed units, etc., etc. "
Now you're stuck with size 50X26 FJ trousers that your sewers spent 6 hours making up all special for Pvt. Snuffy. Apparently Pvt. Snuffy gains weight faster than you can sew.
"Custom Orders" start out innocently enough as essentially taking requests, which rapidly morph into demands, which finally hatch as a full blown "Fulfill My Fantasy" situation. (No sick jokes intended. Just this once.)

The problem here, (OK the biggest problem) is trying to decipher what somebody has pictured in their mind, then creating it.

The major problems with filling custom orders are:
Indecision: These guys go crazy and call daily wanting to tweak the shade of green on their helmet or change the color of thread used on their M43 cap. It's bad enough to offer helmets, but when you have their personal helmet, people get very cagey and go nuts if they have any suspicion that their helmet is not being treated with the respect it deserves.
Handicaps: Many types go deaf the moment you accept the job. The results are threats of lawsuits and complaints to the Better Business Bureau because they couldn't reach you on the phone for 3 days. (The fact that you told the moron that you would be gone to a show 500 miles away for those 3 days is not important.)
Rudeness: Custom orders inspire people to find your home telephone number and call you at 3 am to check on their helmet. They're afraid it might be cold or need it's litter box changed. And to remind you that they wanted a Normandy Camo and not a Nijmegen Camo.
Inefficiency: Custom Orders are incredibly inefficient. It takes the same amount of time to cut 50 tunics that it does to cut one. In case it is news to you, labor costs in the US are high. In the time it takes to pattern, grade, cut and sew Pvt. Snuffy's size 58 short "Rommel" tunic in splinter camo (that will get returned because he doesn't think the twist of the thread is accurate) we could have made half a dozen SS M43 tunics. I doubt even Pvt. Snuffy is willing to shell out $1800 to have a custom camo desert fox impression.
Impatience and a total inability to comprehend much of anything: Custom Orders require a delivery date. Even if you warn them, in the clearest fashion imaginable, that their order will take 6-8 weeks to complete, the calls and complaints will start at the 3 day mark.
"Just calling to check on Heinz. Oh, Heinz is my helmie-kins. I give all my helmets names to fit their personalities..."
We have a close, personal relationship with Murphy's law around here. A high percentage of custom order customers are very impatient, and rarely have any sympathy for things like your air compressor breaking, UPS strikes, other people's orders being ahead of their own, running out of decals (thread, paint, wool, etc.), and in general they cannot understand that we don't have the ability to wave a magic wand and make whatever it is they want pop out from between our buttocks and be teleported to their door in nanoseceonds.
Talent: We're not good enough to fulfill the fantasies that would be requested. If I could look at the helmet on page 65 of Ralph's Pictorial History of Nazzee Helmites and knock it off, that would be different. Honestly, since we do not have a tailor in house, we do not have the capability (at any price) to take the measurements for a gal who's 4'10" and 387 pounds and make her an Eva Braun outfit. Even if we wanted to to it, we couldn't do a good job.
Not everyone who wants a custom order is a wacko. We know that. However, the 20% who are, ruin it for the 80% who are perfectly sane. Until we can cull them out over the phone, there will be no change in our policies.
Bottom line: Unless we charged an enormous amount of money, custom orders are not viable for a business. If you do them as a side job or a hobby for your buddies, it will work. It sounds like a neat idea, until you actually try it. That's why we won't do them. We're not being mean, arrogant, cruel or snotty. We've learned our lesson and just know better than to let this monster out of the box.

Hope for those who demand special services.....
The closest we may come to closing the gap between stock items and custom orders will be, maybe, possibly, sometime in the future:
Sewing insignia, minor alterations, minor modifications (such as adding extra pockets to jump jackets or the like).

I want a Custom Order! Now!
There are some masochists out there. Here's our recommendations:
Uniforms (German): Bill Bureau: www.stby.com/bbm/
Helmets (US, German, Japanese): Eric Grigsby: egrigsby44@aol.com
Sorry, we don't know anyone doing special request GI uniforms. Bill Bureau may know of someone.