Im using a friends sears pull behind 48" core aerator and it does a very good job.. I can get 2" to 3" plugs from my clay soil the day after a rain using about 80 lbs of weight..
Granted its not very heavily built and probably would not hold up to commercial (or even heavy consumer) use - but for doing my yard 3 or 4 times a year you cant beat what it will do for under $200.
Just my thoughts..
Brian