The classic graphic EQ is nice. More bands {sliders} = more
tweakability and it's more of a general purpose EQ. The parametric
EQ is more specialized, usually used to fix specific problem areas.
Both work.

The next issue is whether you buy home audio gear or pro audio
gear. You have to figure out your front end electronics as
pro audio interfaces a little different than home audio. If you have
home audio gear try looking for affordable home audio EQ's. I chose the pro audio route because Behringer is hard to beat from a
price/performance point of view. You just have to design your front
end around pro audio.

>>How much should I pay?
The DCX2496 is a pro audio piece of equipment, it's a digital
crossover with some parametric EQ and other stuff. Cost on
these is $250 shipped. The DEQ2496 is specifically an EQ. I haven't
checked home audio gear recently so I can't point you in a direction
other than maybe http://www.audiocontrol.com

>>Have you ever bought anything on ebay?
Buy from a reputable seller.