There is a good reason why she's like that. In the light novel, she's had to deal with Bray's incompetence as a party leader and not being able to rank up as adventurers. They're barely D-Class and they haven't ranked up in a long time. Technically speaking, they SHOULD be making enough money to afford sleeping at an inn. Unfortunately, guess where most of that money is going to? That's right, either it goes to Frey's family bakery, or they botch the quests so badly under Bray's leadership that the rewards are lower. In fact, after Iginis leaves the party, Bray's team suffers a lot due to the lack of 'fire' power, literally. They can't take higher-paying jobs like monster-hunting. Bray even tries to get Iginis to rejoin the team, but she refuses because she knows they'll drag her rank down and she'll get the short-end of the stick when it comes to her paycheck. She doesn't officially join with Touji's team but she does partner up with them every now and then.