Thanks to the struggling economy, the word "vacation" has become taboo -- so taboo that a substitute word, "staycation," was added to the Merriam-Webster dictionary in 2009. Although the web is bursting with deals and advice on vacationing on a dime, let's be honest: There are some cities that are, in one word, expensive.To separate the reputed budget-busters from the truly expensive cities, UBS Wealth Management Research, a Swiss-based global financial services company, conducts a regular Prices and Earnings report, the most recent of which was published in August, 2011. The study, which covers 73 of the world's major cities, analyzes economic factors such as currency strength, plus the price levels of travel basics like hotels, food and transportation. Using these elements, UBS is able to determine the places that most accommodate bargain travelers and the places that most likely empty their pockets.According to the report, cities with strong currencies are able to support higher prices. The converse is also true, as you'll see most prominently in the United States. For example, since 2009, New York has become significantly cheaper to visit than it has been in the past. The reason: Our greenbacks don't carry as much weight as they used to. Major European cities -- such as Paris and Rome -- also became more affordable over the past several years, while destinations in northern Europe (like spots in Norway and Sweden that have weathered the economic crisis well) have been able to keep their prices high.So what does this mean for travelers? The good news is that vacationing here in the U.S. has become a much more budget-friendly option, while some of the world's most prevalent tourist spots are edging their prices down into the affordable realm. Still, there are several cities that frugal travelers -- no matter how bargain-savvy they may be -- should avoid. Based on the Prices and Earnings report, here are the 15 cities most likely to devour your travel budget.