Why a IIgs?
I'm one of those who own classic computers to tinker with them. I have for a long time had my eye on the Apple IIgs. While I'd love an apple ii just because of its historical importance, the IIgs seems like the "ultimate" model. However, I'm far from knowledgeable on the subject. But as a commodore fan by heart, it is the most "commodore" model given it not only have a sound chip by the same guy that made the famous sid chip (Robert Yannes), it also have the 16 bit version of the 6502 - the 65C816 by Bill Mensch. Now that's probably not very relevant, but I like the connections.
So beside the tidbits about the machine, I'm not sure i want the "ultimate" one. I just want one i can easily access the apple ii and iigs lib of software.
Now my wish to stay retro ends at physical medias. I'm not that keen in relying on floppies. I want a modern sd/cf solution for my media needs - also so i easily can transfer from my computer to this. I also need sufficient memory and so forth. So my question would be
- what do I look for when buying a IIgs?
- what add ons do I need for my modern use?
- I want an ntsc machine, but my monitors is either PAL or VGA. I do have spare external scan doublers, so i presume i have to resort to that. I haven't room for a separate monitor for it, so it has to be connected to one of my others (pal commodore 1084s, pal microvitec m1438s or a SVGA CRT computer monitor). However, I read the PAL 1084s can do NTSC as well but I haven't tried that myself.
So any input on the subject? 
The IIgs is definitely the powerhouse of the II line. The IIgs is compatible with software from the 8 bit machines in the II line.
It is a good thing you want to stay away from physical media. I've had little success even with new old stock floppies.
Some technical things to look for:
* A ROM 03 machine comes with 1MB RAM on the motherboard, four times as much as the ROM01 machine.
* Don't buy a ROM 00 machine. Not likely you will find one anyway.
* If you go with a ROM 01 machine, make sure to get RAM - it is best to find one that comes with a RAM card.
* Accelerators are nice but I have never seen one for under $200 U.S.
Some tips for buying:
* A IIgs with a printed Woz signature on the front is not worth any more than a normal IIgs
* In my experience, buying a IIgs with RAM in working order has been $50 to $100.
Modern enhancements:
* Vince Briel sells a number of modern enhancements for the II line. They come in kit and assembled forms. I suggest the RAM card. http://www.brielcomputers.com/wordpress/?cat=22
IIRC, anything over 4MB is not DMA'd.
* Software is easily obtainable. http://mirrors.apple2.org.za/ftp.apple.asimov.net/
* Internal storage via methods of the IIgs' time are hit and miss these days. Things like SCSI and floppies are showing their age. You should keep your eye out for the next run of CFFA cards. http://dreher.net/?s=projects/CFforAppleII&c=projects/CFforAppleII/main.php
* Want to put your IIgs on the internet? Uthernet II is in the works. http://a2retrosystems.com/
* I have yet to pick one up, but my understanding is the AppleII Pi can handle most if not all of the tasks above, albeit via emulation. https://ultimateapple2.com/catalogzenQI/index.php?main_page=product_info&cPath=1_3&products_id=13
As far as the monitor situation, I can't speak to the NTSC/PAL issue since I've never had to find a solution, but the machine does have a composite video out. Maybe there is a route you can take there?
Also, if you haven't tinkered with the Apple II line very much, I highly suggest you get a copy of this book: http://macgui.com/newa2guide/