As the gulf separating luxurious first-class air travel and economy continue to widen, however, that could be a thing of the past. Airlines have already started testing “Basic Economy” fares, which do not include the above “perks.” Now, Delta, United, and American are planning to roll out this class of ticket across their entire domestic networks, as well as add it to some international routes, The Wall Street Journal reports.

Going forward, then, travelers will need to pay even closer attention to the type of airline fare they’re purchasing. If you’re buying a “basic economy” ticket, you won’t be assigned a seat until the day of departure (read: you’re sitting in the middle), the ticket can’t be changed, and often, you won’t be allowed to bring a carry-on bag without paying an additional fee. While good news for thrifty travelers, it’s a disaster for passengers who make the purchase without fully understanding what they’re getting themselves into.

The difference between basic economy and standard economy fares are typically between $25 and $40. While the cheaper flight might be tempting, if you’re paying to check that bag rather than carry it on ($25 each way with most airlines), or really hate sitting in middle seats, you might be better off spending the extra cash when you book rather than shelling it out later.