Need suggestions for rolling carry on type bag

I recently purchased a lowepro computrekker plus that works great with all my gear and is the perfect size. However, when I add a laptop, it becomes very bulky and uncomfortable. So I'd like to take a look at some rolling cases that meet carry on requirements.

Not looking at spending $300 on a new one, and would prefer to pick something up used of eBay or Amazon to keep the cost down.