Beautiful work. I have owned several Cricuts and other die cut machines since the first Cricut came out several years ago (back in 2006). Cartridges were never cheap and I don't know what used ones sell for now or how easily they are to find. While I still have mine and a ton of cartridges it is never used- I moved up to other cutters that use software that let you create and cut to them without the need for cartridges. There were two programs that you could get to create your own designs and work with fonts on your computer. Provocraft sued them though to prevent them from working with their cutters so they don't work directly with that brand. There are "workarounds" though so if you are ever interested in learning more on that, let me know.
I would recommend getting a printer if you are wanting to regularly use patterns for your scroll saw. It would be much easier then be limited to the Cricut and their cartridges and you can get a printer relativity cheap (probably cheaper then getting a few cricut cartridges that can only be used with that machine). The printer would allow you to do more with a ton of free patterns from multiple sources like here in the Village library and from Steve Good's blog http://scrollsawworkshop.blogspot.com to name but two sources. (Steve has a few puzzle patterns). Then Al also gives away a ton of free patterns on his site http://baggetta.com and has some he sells, some of which are puzzles. The animal puzzles referenced above that Scott (Iggy here on the forum) does can be found on his site here: https://www.woodcraftbyscott.com - he sells them but they are created by Harvey Byler.
If you don't have a printer, and don't want to get one just yet - you could take patterns that you get online and download to your computer and send those to print at a print shop like those at Office Depot, FedEx copy centers, etc. so that would be another option for you to consider if you found a pattern you wanted to use but needed to print out.