Everyone has great tips for you. You may also want to look into what uses you can get out of which crates.

For example:

Wire crates can fold down and usually have a carrying handle on them, taking up less space when not in use or traveling. When you get coated wire crates they are easier to clean & last longer.

Mesh crates are much lighter than the wire crates and also fold down, but they are not as sturdy. Not sure how easy they clean up and how many washings they can handle though.

Plastic ones are the only ones allowed on planes, so if you travel via air fairly often it may be easier on your pocketbook to just invest in one of those. Easy to clean.