A waste of money? It really depends on your perspective and what's affordable to you. For me, I have some rather expensive bikes so $2500 for wheels isn't that big of a deal. In fact, I have several sets of wheels in that range. If you're scraping together pennies than it's more of a big deal unless your goal is to be the next Lance.

Let's make sure we're talking about the same thing. Light weight wheels are usually considered climbing wheels. Deep dish carbon wheels are usually considered "aero" wheels. Light weight wheels are generally not the best bet for clydes because they are made to be light, not strong. Deep dish carbon wheels are not generally really light. They may be lighter than your OEM wheels but they aren't really "light weight" wheels.

Performance wise, will a light weight or aero wheel outperform a standard wheelset? Sure (and you'll definitely notice it) but the question is by how much and what the parameters are. If you are talking just "lightweight" wheels then they're going to be an advantage for you if you're a billy goat or love sprinting your buddies to the next street sign. How much of an advantage is debatable but it's not real huge in the grand scheme of things.

Aero wheels will increase your speed but not unless you are usually riding over 20mph. There are diminishing returns below that.

Personally, I'd take an aero wheel long before a light weight wheel. If you get a deep dish carbon wheelset you get the added bonus of having a (generally) stronger wheel than your OEM wheel. Deep dish carbon wheels should have no problem with your 235lbs. In fact, That's about what I weigh and I have them on my single and tandem! I also ride a lot, around 6-10,000miles a year.