regular NDS support should be a must, don't stock too heavily however.
try small batches and see how they sell.
I have a dsphat and i really hate the fact that the only reliable place that i can buy new cases from are gameyeeeah(hinge broke lol). its always give and take with all these sites, since they only have SOME NDS products.
styluses, slot 2 "phat cards", case replacements etc. Theres never a single site which has everything i need.
I don't know, it could be cause the dsphat accessories dont sell but just try it 'mkay?
have a large selection of slot 2 cards since slot 1 are usually the same(rly, just a few differences, not like EZ4--M3minisd--SCminisd)
and just like mentioned before, use a clear table. dont use lists, people get tired from them quickly. the table could give you a chance to actually explain what everything is for.
for the site, use a simple black font thats not too small but instead of using a white background, use a background color thats easy on the eyes, like creamish yellow etc. but make sure to have a good contrast between the text and background.
Also, if you're gonna sell parts, have a few
tutorials on your sites and link from the parts. this would be ABSOLUTELY GREAT!
no more worries or headaches from looking stuff up on the internet.
last but not least, make sure that you have a very clear FAQ and information about policies and shipping, offers etc.
its frustrating to have only a few lines of text and then have to go on the forum or send an email because you dont get it.