Currently you can find a dozen of G1000 system makers on the simulators market that sell their products for price ranging from $600 to $xx 000. Some of these expensive systems are positioned as "professional, certified" devices for flight schools, they may even have their own software, but most are proclaimed as suitable for "home cockpit builders"! You can estimate whether this is really suitable for you.
Some of them are molded from ABS plastic and absolutely indistinguishable from real Garmin, with all right corners radius, colors, texture, backlight, every millimeter is a piece of art (you can hang it on the wall and admire it, blowing off the dust, or you can use it as spare parts for your real G1000 mask in the plane when it is broken).
The others are more simple, have a flat bezel surface, or it's just a mask on the monitor, with or no backlight, made from plexiglass, you do not feel sorry for scratching them with a screwdriver by accident - ah, big deal, for $800-1500:
Here are some examples of such products that I found, mostly for MSFS/P3D, some universal (MFD+PFD+Audio).
Full replica, exact copy, molded ABS, full set - $4500 - 6000
Visually like real, flat surface, inputs work as HID device- about $3000
Visually less like real, flat plexi mask - about $2000
Simple plastic/metal mask (box) fixed on 22-27" LCD monitor - $1200-1500
Bezels G1000 for iPad (for $600-1000)
Also, you can find at least one G500/G600 avionics replica for about $1000, it's also LCD screen with the bezel for displaying MFD/PFD using one of the known G600 program (note: the photo on the left is the real G500).
Some other devices such as GPS (430/530) are sold for price of about $200 to $1000.
You can estimate prices by just learning more about how all this works. You may be surprised. Read below about this.
Why does no one produce G2000/G3000 ? Maybe because it is much simplier, it is just a simple frame with 12 absolutely similar buttons? How can you convince people that this is a "very complicated" and expensive device? No chance. "C'mon, it's just a small monitor with a row of buttons!" And so it is.
Of course, I don't mention its control touchscreen here.
Each hardware module for the simulator performs two functions - input control (switches, buttons, knobs) and data output (displays, indicators and pointers). And, in fact, such modules as G1000, GPS (430/530), EFIS and other "complex" modules that have a TFT screen for displaying information from the simulator, are some of the most simple devices!
They are even simpler to make than some of the switch/annunciator panels or an autopilot module! Why?
Those several buttons (and 2-4 encoders) are also doing nothing for the module itself.
All these control elements are used to send commands to your simulator, using one of these two methods of USB communication:
So, as you can see, the structure of such device is very simple - it consists of only 3 parts: LCD display, one or several small PCBs with a few buttons connected to some input controller, and cover (bezel).
To send input commands to the simulator all the buttons are connected to the HID or "virtual serial port" controller (one small chip) which is connected to your computer's USB socket. All communication is provided either by X-Plane plugin (or program in FS/P3D), or by standard HID device protocol.
ArdSimX and SimVimCockpit software uses "virtual serial ports" for communication between the plugin and the controller board (if you're not using Ethernet connection).
As such, using our interface you can connect (directly or with extension boards) all buttons, switches, encoders to the controller with uploaded SimVim firmware and configure them for this specific device with ease.
Do not think that you need some "special" LCD for your PDF / MFD / EFIS / GPS. In fact, you can use any available LCD screen, even a very old LCD monitor that you can find for free in your house, or buy on "second-hand" market for $5 ... $50.
As an example, I can count about 15 old monitors and LCD screens of different sizes stored in my household, a few of them are our own old used monitors, others were purchased for prices from $10 to $50.
I don't know why you would need your Gxxx avionics to be a "detachable" module, if you are building you own panel of a specific plane. Or, maybe you are thinking - "oh, if I can make this for myself, so, I can make more and start selling"? Because, if you want it modular to carry it between your panels (supposing you have more than one panel in your home that needs this module), it is still cheaper to make it stationary (as bezel) for every panel.
1. If you absolutely want to make it as "module" you can find and buy the LCD screen or small monitor that exactly (+/-) fits your module screen size. It can cost you from 30 to 150 $$.
Here are some examples:
Buttons (total cost $2-5)
Encoders (total cost $5-20)
LCD screen (old monitor LCD - $20-30)