Sorry, I may be late but maybe this will help someone else.
You can find a used decent cage for as low as $150.00 dollars on craigslist.org. I built a cage a while back. The frame was wood and I used plexi-glass for the sides instead of bars; it prevents food debris from falling all over your floor. I would recommend your cage to be at least 3.5 ft wide, but the wider the better. The macaws need to be able to spread their wings and, given the fact that you will have toys hanging inside the cage, I find that 3 feet is not wide enough. When coming up with a design, you need to keep in mind ease of cleaning, accessibility of food/water bowl in relationship to the location of the cage. You should be able to remove bowls without opening the door to the cage. 5ft high is fine, but again the higher the better. If using plexi-glass, you can try hanging the perches from the top of the cage. Also, it is very important that you are able to easily take your cage apart in case you need to move it to a different room or take it outside for full cleaning. You can't fit a 3.5 feet through most doors. With that said, if you're looking to save money, buy a used cage. If you're looking to have a cage that looks as you want it to look and have that great feeling you normally get from building something with your own hands, then you have to be willing to spend more than $100.00. Believe me, materials will run you up a couple of hundred bucks.
Just my 2 cents.





