You either get into speedcubing and get high end cubes to improve your performance, at least of the official categories and a couple must haves like the Mirror cube.
And / Or
You start collecting cubes and puzzles of all kinds and shapes (yes, even non-cubical :o). You start to acquire custom cubes built by hand by artesians or niche brands.
For the love of what's good in this world, stick to that one budget MJC set of competitive cubes until you are actually 10 or 20 seconds behind the world record
I personally love the feel of the MoYu RS3M MagLev. And I think it was like 15 bucks.
And don't be afraid to go to chinese distributors like ziicube.com
Saves a lot of money by going directly to the source and buying in bulk if you can, to alleviate shipping cost.
I have a Tornado just sitting in my basket going "BUY ME, BUY ME!" but I've only just yesterday got a sub 40 second solve so it's staying there. Plus I'm broke.