Really need more info.
Headphones - Open/Closed? What're you using them for?
Amp - What inputs? Do you want the option to go surround or add a sub later?
Headphones in your budget? The BeyerDynamic Dt770s aren't bad, but like NiHaoMike said you'll want a dedicated amp/DAC, especially with the 250 Ohm model. I almost want to say go with the Phillips SHP9500s and get a basic USB DAC/amp combo, then upgrade later if needed.
Speakers? I like the Klipschs in my sig and if you keep an eye out they retail for $100 new, but they still need a small basic sub to shine (as will most of your typical small 5.25"/6" bookshelf speakers).
Amps? I agree with a budget of $100 you'll want to browse for something used. I've had not-so-great luck with the true bottom of the barrel amps, and my current receiver, the R-S202BL, was one of the cheapest ones I was comfortable with based on reviews and all that. But they retail for $150.