Have you considered a table-top reciprocating saw like the Worx Bladerunner? Personally, I would rather go that route only if it took sawzall blades, but its an option.
On the other end of the spectrum, you could always slap a worktable on a portable bandsaw, like Blondihacks does. She shows how to make one here, but there are a lot of options on the market.
Personally, I put a WEN portable bandsaw on such a stand. I went with the corded version for the price, power, and variable speed. If you look at the reviews, the only complaint I recall seeing is that its "heavy". I've got it on a stand, on a stool that I cut-down to put the table height just-below the height of my saw-horses, and I move it where I want without problem, so "heavy"? Not for my uses.