Oh, it has to be the interconnects and speaker wire. Without these very important components, no sound or video will be heard or displayed.
Now, when you plan on budget, make sure that you spend AT LEAST 90% of the budget on the all important speaker cables.
Ok, maybe the budget part went a bit over the top.
Seriously,
1. Surge protector & line conditioner. No, not one one of them "I can stabilize your voltage and remove 10,000db of noise" line conditioners, rather a decent surge protector with built in 60db of EMF/RMI noise reduction. A decent surge protector is critical (it is lightening at my house as I write this), and for just a few extra bucks I also have noise reduction .... which does come in handy as the lightening strikes the cable line a few miles from the house and produces all that garbage that I no longer view or hear. Why spend $20 on a surge protector when $50 gets the surge protector and line conditioner?
2. Room size .... why bother having a nice pair of Martin Logans in a room no bigger than a closet?
3. Speakers
4. Room Acoustics. Great room acoustics with crappy speakers, still equals crappy sound, and room acoustics can be improved in the installment plan with WAF furnishings and decor.
5. Video display proportional to the quality of the source player. Having a mega buck 100" plasma screen is a waste of money if your source is a 20 year old VCR.
6. Electronics (receiver, dvd etc) proportional in quality and capability. Again, no Denon AVR 5806 being matched with a Awia MP3 player.
7. Interconnects. Good fitting RCA's are critical. And a little insulation never hurts either. Rat Shack and Wally World are great sources to keep the budge under $100 for a whole fist full of decent interconnects.
8. A decent rack to hold the goodies. Say after me.... "heat is my enemy" and repeat as often as necessary in order to doctrinate the W or GF that a clunky rack is more important than matching pillows on the sofa.