My question involves collection proceedings in the State of: Michigan

I broke an apt lease in 2004 (not my proudest moment) and since then I have had maybe 3 collections letter over the past 5 years. I owe about $3500 which I cant figure out how they got that amount but really I dont ever plan to pay so I guess its not that important. Its been reported to the credit agencies and comes up on my credit report, which does bother me because its a large amount and weighs down my score.

There was never an eviction proceeding or anything.
There is no judgement against me in any court. I have verified this with the courts.
The apartment complex has since been sold to new owners.

Is this still a valid debt? (legally not morally)
When is the statute of limitations up?

Thanks for any info anyone can provide.