If one doesn't have a Miter Saw is there a low-cost tool that can be used to cut corners on Crown Molding?

in the past i have used square blocks in the corners to avoid having to cope or miter the crown just make sure you use large enough blocks to accept the crown as it lays on the ceiling. this way you can use a hand saw to cut ninty degree angles

You can get a manual miter saw/box for around $30.00.

Not that this answers the question but I used a miter box and saw for the longest time and it was ok because didn't know any better. Then I got an electric miter saw and wow, what a difference. Whereas with the box, each cut takes 3 or 4 minutes, with the electric saw it's a couple seconds. And whereas with the box, you'd better get it perfect the first time (which rarely happens), with the electric saw you can err on the heavy side and shave the cut to perfection with a second cut. The after a while, you'll get a feel for all aspects of the electric saw, the width of the blade, where to mark the wood and you'll get perfect cuts every time. Consider renting an electric miter saw, you'll never go back to the box.

A miter board. It is a board with angles cut for your saw to go into to give you the angles you need for the crown molding.

SHOCKING! Top UK retailer Argos announces Santa Claus is not real! http://i.imgur.com/slnqs.jpg

Polish the sides of your saw and you can cut 45 and 90 degree angles by looking at the reflection in the saw. If the reflection is at a 90 degree angle, then you're cut will be a perfect 45 degree angle. I can cut 45s without a miter box. Practice a bit first. That's the free solution. Otherwise, buy a miter box, as mentioned.

use a mitre box

If your painting it white, don't waste your time coping.Especially if it's a big complicated molding.

Renting a power miter saw will give much better results, and save wood.