Let's leave morality aside for a moment, and talk about the wisdom of abusing a potential employer's hospitality. Companies typically don't pay travel expenses to meet prospective employees unless they're pretty serious about hiring them, and the position is specialized and important enough to warrant the expense. In order to get such an offer, you probably have to be at a level of skill (or position) where good relationships within your community matter to your career. If you're not sincere about the job, and they discover it through your words or actions, it could damage your reputation.

Additionally, finding the job and preparing for the initial interviews requires a significant amount of time. In order to do the in-person interview, you'd probably have to take a day or two during the week, which means arranging an absence from your current job. You may have to lie to your employer about the reason for the absence, and use a vacation day or unpaid day, which may be worth more to you than a sponsored $400 ticket. Also, you'd run the risk of someone at your company discovering the reason for your absence.

And who pays for interview travel any more? My current client won't even pay to have me come to Philly to work with them, and we're doing a project together.