Of course, something may have been cheap because it was produced in a place with lax environmental regulations (so lower compliance costs) and shipped via bulk freight options which dump a lot of nastiness into the atmosphere...
Yes, certainly. But if you compare two products made in the same country/area they nearly always have about the same pollution load, so price is an excellent way to compare them.
"bulk freight" being a problem is not correct. Bulk freight is probably the best way to ship something, and any energy cost is contained in the final products price.
A rule of thumb: the cheaper it is, the less energy it took to make it. Some more details: http://news.ycombinator.com/item?id=346912
Be aware that less energy is not always equal to better for the environment.