I have owned the C9 and the carbine in 9mm
as stated above ugly yes! reliable? hell yes
does the c9 look like a cheap power drill? yeah kinda
can you bury the power drill soak it with mud an it still work? NOPE the hi point will though, every damn time, its just much too ugly to die that easily.
they have amazing customer service as well, so they make up for the looks by having a great personality!
If that is what you can afford, get one. You can not go wrong with it. Now having said this, customized? Uhm probably not a lot of options much like there were no sport options on a Yugo. Cheap is cheap, and rarely gets decked out in bling like a thousand dollar gun would. Factory seems to be the place to get most or any thing for them.