Fusion's hobby license is solid, but watch the 10 editable document limit. For purely basic shapes, FreeCAD is a steep learning curve but it's truly open source, no account needed. Just be ready for a different workflow than the polished commercial stuff.
@derekl79 makes a good point about reading the fine print, but what kind of project costs $500 to get locked out of? Were you trying to open something super complex?
Man, that's rough but I gotta ask, did you really need to spend that much before checking the license? Those trial locks are usually in the fine print. For basic stuff, Fusion 360 has a free hobbyist license that works fine, just don't use it for a business. I've messed with it for designing custom brackets and it gets the job done without any surprise bills.