I would buy star cases for any of your very valuble figures, particularly ones that are hard to replace, or just plain expensive. Many dealers sell them at very reasonable bulk discounts in dutch auctions on ebay.
That having been said, I have a few ideas for you, that aren't too expensive.
1) Bankers boxes. You can buy them just about anywhere, especailly office supply stores, and they're fairly cheap. They hold quite a few carded figures (20+, stood upright, depending on the size of the bubbles). Like figures store best together since they have similar sized/shaped bubbles and can face alternate directions to fit the most in the box. Bankers boxes are easy to acrry, they stack well,a nd are sturdy so long as you don't put heavy items on top of leight-weight boxes. Five boxes cost maybe $5. Prices vary depending on sales. They also come in a legal size, that is very long, but akward to use. This size actually holds a b-wing fighter.
One downside to bankers boxes is that now days, the lids have a very short (one inch) lip, so they do not stay on as well as they used to, and probably need taping is they are going to be moved a lot. Older boxes had a two-inch lip that wasn't going anywhere.
2) Comic boxes. They come in long or short boxes (you can also get magazine width boxes too). Available at your local comic shop for between $4-$8 a box. They are more sturdy than bankers boxes, but a little more akwardly shaped.
3. Sterilite plastic (rubbermaid-like) containers. These are available at Walmart and other places. The ones I use are about 12" tall, and are maybe 12" X 7". They are clear plastic, with a colored (usually blue) lid that snaps on top. These are nice becase they absolutely will not crush, have a carrying handle, and are see-through. However, they do not hold many figures, no more than, 10-12 POTF2 figures, probably 4-5 Saga. I used then when I only had a few carded figures, but then I switched to bankers boxes. I still use them to hold other things, including my Cinema Scene cardboard backdrops. I believe they cost $3-4 each. They are big enough to hold 4 figures in Star Cases.
Anyway, I recommend bankers boxes for ease of use and cost effectiveness, but any of the above would get the job done.