dont get a controller unless your playing car-race games.
get a good gaming mousepad and mouse (g602-g700s-g502-G600) im a logitech fan and razer hater but some ppl recommend razer
a good keyboard like (G510s - crosair vengeance mechanical keyboards-G19s-G15, ect )
steel series is also good i think
i have a razer keyboard, i hate it, hard keys, sometime freezes , stupid layout , i press macro button accidentally so much !
i always got logitech and havent had problem yet , a 4-3 year old mx510 as a gift ! (best mouse ever ! still like it ) a around 5 months old g602 that changed battery around 2 weeks ago
im not good at sound ! but i use a cheap awesome logitech speakers (forgot model) and im happy with it ! i dont really have a good headset ! (a philips headset)
a keypad if your into mmo or even some fps ! (like g13 i dont have one, dreaming of it but i think it Really helps ! + its so cheap)
dont even think about controller for fps, i headshot you 10x times with mouse before you even see me and start aiming with a controller
what i would get :
a logitech or razer speed mousepad
a g602-502-g700s-g500s-G9x-g400 (look for ergonomics , buttons , for me the G602 is best because of enough buttons and awesome ergonomics and just enough dpi! )
a G510s
maybe a g13
thats all !
Edit: my cousin tells me steelseries keyboards are so horrible ! as i said, i dont exactly know about steel series because i never saw them !