Do you only get to cruise if you're rich?
According to the CLIA (Cruise Lines International Association), fully half of today's cruisers have household incomes under $60,000 a year.
Prices are very competitive, especially considering cruises are all-inclusive, meaning your cabin, entertainment, and meals are included. This makes cruising more affordable than other vacation options. In many cases, you may even spend less than you would taking a road trip and renting a cabin by the lake (just consider the price of gasoline these days).
Today, cruises are departing from more ports than ever as well, so if you live near the coast, you may not even have to pay for airfare.
In other words, you definitely don't have to be rich to take a cruise.
If money is a concern, know you can get some great deals by booking well in advance (as soon as the cruise is opened up for bookings) or at the last minute (great for people who can pick up and leave on a moment's--or at least a couple weeks'--notice).