I think it's definitely easier to attain a double major depending on how closely related the fields of study are. For example, a computer science degree could be fairly easily combined with a mathematics degree within a 4 - 5 year curriculum.
Since the issue at hand is more of a financial concern for you, I'd advise to do your best to complete your primary major coursework first. If some classes are possible to pick up along the way to achieve a double major then go for it. If not, then you could just settle for a minor since it should be less of a time and money investment.
As for employers, they value different things in prospective candidates. However, if you meet a percentage of the general job requirements then you should be fine pursuing your career with the knowledge you possess. Keep on learning after you graduate despite what degree(s) you have attained. It's the best competitive advantage since knowledge can overtake credentials in the long run.