The advice for most hobbies is to buy the best tool(s) you can reasonably afford for your use case.

And I’d say same for sex toys, too. Buy some cheapos of various types to try them out if the price is right (and the materials aren’t sketchy).

You may want to try to figure out what sort of sensation you enjoy the most, and then search for toys that provide that sensation or can augment the sensations you already have. If what’s lacking with your handheld wand is, well, a penis, maybe you could try a ‘thruster’ toy, instead of going for a full on sex machine. If your setup is lacking in power, an original (corded) hitachi wand that’s plugged into a motor speed controller would do the trick. If it’s control, then maybe a good quality bullet vibe, like the we-vibe touch.
Of course, if it’s the vibration sensation itself that isn’t cutting it, then look at suckers, point vibrators, and whatever else that looks interesting.

Strong recommendation for She-Vibe as a vendor right now. They tend to have pretty good stuff and not terribly overpriced.