I just noticed MakerBot discontinued their 5 pound rolls for HDPE.  This page is essentially taken down.  However, when it was last up it contained the following product description:

Update: Discontinued. It’s not fun to print with this stuff.

This is HDPE plastic aka High Density Polyethylene aka Milk Jug plastic. This is a nice, smooth, high quality plastic. It comes as a filament in 5lb coils with a diameter of 3mm.

This plastic is cheaper than ABS, but has a higher shrinkage factor which makes printing large objects more difficult. It does have a much lower coefficient of friction so you can print things that are very smooth.

I’ve never printed with this stuff.  Have you?  A higher shrinkage factor than ABS sounds pretty awful.  Then again, I mostly print fairly small parts, so then again I might not care.  And, for the last listed price of $30 for a 5 pound roll… it’s a dirt cheap printing option.