Click here for jumpsuit reference pictures
There are 3 different grades of flight suits that can be used to replicate the originals.
CWU 27/P Flyers Coveralls
The CWU 27/P Flyers Coverall is the flightsuit that is currently issued to US Military pilots and is the most accurate flightsuit available in terms of screen-accuracy. The suits are made in only 2 colors, Sage Green and Desert Tan, the latter being the accurate color. They run anywhere from $30 for used ones on eBay to $200 for brand new ones. They include all the features of the original suits with the exception that most have black paint on the zipper pulls, which if removed will usually reveal brass. These suits are a very mellow shade of khaki and do not usually require any dying, which is a good thing as Nomex material contains no cotton or polyester, instead they are composed of synthetic meta and para-aramid fibers, designed to make the material heat-resistant, but also making it nearly impossible to dye beyond anything but a very light gray tint. Nomex material is heavy and does not breathe as well as other materials making these suits kind of stuffy in warm or muggy weather. Also, they are designed by chest size not waist, and they only go up to a 52 making them unwearable by large or overweight individuals.
The best place to purchase this type of flightsuit online is eBay. They are easily found by searching using the keywords "Flight Suit Tan"
See these search results for example
Click here for a pic of a Nomex CWU 27/P in real life.
Tru-Spec 27-P Flightsuit
The Tru-Spec 27P is considered to be the happy medium of flightsuits. It combines the features and benefits of a CWU 27/P but in a lighter, more comfortable poly/cotton blend although the blend is heavy in poplyester which can make the suit a little warm to wear and gives a bit of an unwanted shine to the fabric. The factory khaki color on these suits seems to be the closest to screen-accurate, requiring little to no alteration. These suits have screen-accurate features such as unpainted brass zippers and a storm flap, however they lack other features such as the lap pockets and the knife pocket on the inner left thigh. These suits are ideal for larger people as they go into larger sizes than Nomex suits do. These can be purchased from Online retailers such as Galls, Army Surplus for Less and Chief Supply.
Click here to see a Tru-Spec 27P in real life
This diagram will show you Tru-Spec's current pocket layout.
Rothco Air Force Style Flightsuit
The Rothco Air Force Style Flightsuit is the third and least expensive option. Their features most closely match those of the Nomex CWU 27/P while being similar in construction to the Tru-Spec 27P but containing a higher cotton/poly ratio. The material used makes these suits ideal for dying and for wearing in hot weather. Rothco suits are also ideal for large people as certain colors come in sizes up to 6XL. Rothco suits come from the factory in a color that is more yellow than khaki and are known to have poor tailoring making them uncomfortable for some wearers who require more length in the arms/legs and more area in the waist and crotch. In addition to this, the breast pockets, especially on the larger sizes tend to be placed lower on the chest than Nomex and Tru-Spec suits.
These suits are plentiful at nearly every local and online surplus store and are the easiest to find. If you search eBay using keywords like "Flightsuit, khaki, L, XL" etc., you will get almost exclusively Rothco suits. The Picture used above is a commonly used stock picture for a Rothco flightsuit and the color in the picture does NOT match the color of the actual Rothco suit.
Click Here for a picture of a Rothco Air Force Style Flightsuit in real life
Click here for a sizing chart covering all three suit types.
Here is a comparison shot with shodanmark's Nomex CWU 27/P on the left and a Rothco Air Force Style Flightsuit on the right:
Now Some comparison shots of mburkit's Rothco suit(left) compared to his Tru-Spec on the right:
they're fat. they take arm length myspace pics.