I'd argue while the technology has significantly increased, prices of equipment have for the most part stayed relatively flat or even decreased. For example, a less expensive, entry level metal halide such as a CoraLife Aqualight 150 watt HQI would have set you back about $300 on Foster & Smith back around 2011. That doesn't include the cost of a new bulb (around $50) at least once a year. Today, the cost for a completely controllable AI Prime HD is about $265 when not on sale. Add about $30 for the mounting arm, and its still less expensive than the Aqualight metal halide. Over 5 years, the metal halide will cost at least $550 considering bulb changes while AI Prime will incur not more expenses so the total cost is still less than $300. Now we can debate the effectiveness of LED vs. Metal Halide in regards to growth rates and color, but generally one can be at least as successful in maintaining high-light requirement corals in an aquarium with quality LED fixture like an AI Prime and the AI Prime is undeniably a significant technological advance from any metal halide available a decade ago. I'd argue the same could be said of most equipment such as pumps, skimmers, etc.. Particularly when factoring in inflation, prices aren't all that different, or are even less expensive, than they were a decade ago, while the technology has evolved and gotten much better.
The one thing I will admit has significantly increased is glass fish tanks, but I'd point out generally the quality on those has also improved significantly.
It also should be noted that there are some products that have become standard that were not even available a decade ago and this may increase the overall cost of an aquarium, but I'd credit some of these innovations with the significantly increased success rates in long term keeping of individual aquarium systems.
The one thing that hasn't changed in decades: aquarium hobbyists complaining about prices!
