Surprised this got resurrected after so long!
Yes it is high. Dues seem to go to building costs as well as to pay for concerts. One fraternity brought Wiz Khalifa (famous rapper) to campus a few years ago. Since the Wiz probably charged $15-20k to make his appearance, at least one kid’s entire yearly dues went entirely toward that concert! Other recent acts to come have been Cherub, Ace Hood, and many others.
Also ATO is the one I had heard of with the $8000 semesterly bill. Often these things are associated with how new the physical house building is. ATO’s was the largest on campus when built by square footage, it was seriously massive. I think it has like 5 floors. Now the new KA house will dwarf it.
Also note that I heard the $8000 figure from a disgruntled pledge who quit. It’s possible he was inflating the number to make ATO look bad (or good in certain girls’ eyes 
).
Finally while the IFC average may be ~$3000 out of house, an average is merely an average. Some of the IFC fraternities do not have a house building, and therefore their dues are probably less than $500 per semester. However houses like ATO and the new KA have to pay for the maintenance and insurance on a 50+ room facility, and may still be paying loans on that facility. Thus it’s reasonable to say there are houses at both ends of the spectrum.
If you’re rushing, you may be nervous about asking what the dues are. I recommend waiting until after you’ve received a bid or are certain (based on rapport with everyone) you are receiving one to discuss financial matters. Perhaps simply casually say, “So what’s the dues this semester?” They won’t mind but if you seem excessively pushy and worried about the cost as soon as you meet them it will put up red flags you can’t handle it.
Hope this sheds some light on the situation.