You are really talking about two very different things here.
I will suggest on the dolly side that the kit from cinekinetic (Australian)with the small board and skate wheels can be used in an incredible number of ways. The pvc water pipe commonly used with skatewheels is easy to get and buy most anywhere, and is even cheap enough to abandon locally after the shoot. The only downside is you can’t make curved track out of that pipe. You can imitate these skateboard dolies by making them yourself if you are mechanically handy. The only hard part is fabricating the angled brackets that hold the skateboard axle bolts. If you have some metalworking tools, it’s cake.
If you have a Harbor Freight store near you, they sell nice wheels and parts for making your own Western Dolly, if you’re looking for something bigger you can ride on along with the tripod. Those can be made steerable to run in a nice curve.
There are dozens and dozens of steadicam imitators for every size of camera and budget. Unless you really plan to use them every week, I’d rather rent than buy one. If you’re planning to use them at wedding receptions, I’d be wary. While it looks cool to wear and use, it is such a huge distraction at an event like that, where you’re trying to not be noticed so you cna get the prety candid shots, I just think it causes more troubles than it solves.
For high mobility at receptions, I would personally prefer a monopod; stable, quick to use, mobile, gets you high-angle overhead “crane” shots in a second by just raising it over your head. And it doesn’t call massive attention to itself. You can get a fold-out foot plate attachment that makes it almost as stable as a tripod. Move, shoot, move, shoot. Instead of moving WHILE shooting. That’s what I like.