If you’re just starting out, I’d look at durability, setup time, storage, and how easy the inflatable is to transport. A cheaper unit isn’t necessarily a better deal if it needs repairs or takes forever to set up at every event. I was comparing different commercial options recently and found
https://gotinflatables.com/, they have a pretty wide selection, so it’s useful for comparing different sizes and styles. I’d also start with something versatile that works for birthdays, school events, and community parties rather than going too niche right away.