I had the 4 floored version of the petco one you listed for my boys for a while.
This one. I found it to be far to small for 2 chins, but I wouldn't have felt comfortable leaving just one chin in there either. Also, the floor is entirely wire, with holes that aren't chinchilla safe, and if you pull out the wire tray, and just leave the plastic one, they can pop it out in about 40 seconds. It doesn't fit in there terribly well. I will say I did like the doors however.
The general consensus, is the minimum sized cage you should be looking for for one chin, is 2' x 2' x 3', though some will argue even that is a little on the tight side.
I was in a similar situation as you a few months back. I ended up building my own cage when I couldn't find something of an acceptable size for the money I had. Took some time, but I'm pretty pleased with it. My $150-200 budget got me a cage 5 feet wide, 5 feet tall, and 2 feet deep. Mind, my budget included hand made shelves, perches, hammocks, hay bags, and liners. Might be something to consider.