Bidders cancelling their bids

Twice this week I've had people bid on an item and then two days later they message me and decide their budget can't afford it, then they cancel their bid. Super annoying obviously, but more to the point is there any consequences for the user or can they just bid away then change their mind? I lost a couple of watchers after the first item was bid on and then it went on to not sell after the retraction. I've blocked both users now, but seems like a flawed system. Am I missing something? (Other than making everything 'buy it now' which doesn't always work well for the clothing section)