cags are a good cheap first bike

some of the mods you should look at are a decent pipe genuine jet pro, or jet pro replica or a fat boy kit , A decent carby like a genuine walbro WT-603 or walbro replica or genuine dellorto 14/14 dellorto replica depending on your budget , i prefer to go genuine with carbs

a boost ported headkit & set of quality reeds are a good upgrade, but need the pipe & carb to get full potential from them

some dealers do a great value package with everything included.
you could try ozminimoto they will ship overseas

this is more a aussie based forum so i cant really advise you on dealers in the USA

daves motors is based in the US & have been a reliable dealer for shipping to australia so that would be the only website i could suggest but you must specify what engine you have to order the correct parts.
As for PBU & ADA they are overpriced & i personally would not buy from them.

if you want top quality Zoccie make alot of parts for cags & are top quality

i hope this info helps