i picked up a zz3 for 800 bucks, 1500 miles on it 
seriosuly, these guys have the best prices on zz4's i've seen
also make sure, if you call and order it, that you ask them if it really has a steel crank in it, and then when you get it, the first thing you do is look... in talking to an engine builder that does a lot of zz4 shortblock rebuilds (local racing series uses them) and he ahs found someof them just have reg cast cranks in them
Steve

seriosuly, these guys have the best prices on zz4's i've seen
also make sure, if you call and order it, that you ask them if it really has a steel crank in it, and then when you get it, the first thing you do is look... in talking to an engine builder that does a lot of zz4 shortblock rebuilds (local racing series uses them) and he ahs found someof them just have reg cast cranks in them
Steve