Thats great suggestin. As i have been scrolling through various forums, a member at another forum dropped in a suggestion and here it is :-

She suggested to have a security deposit which would be refundable if member hasn't abused or lapsed in renewal/payment. She advocated that such a deposit would drive away leechers but at same time let me have competitive pricing. And since it is a refundable security deposit (*conditions applied*), it shall not affect genuine clients much but only leechers/ ultra-budget clients (as you mentioned above )

I have seen similar concept but not in hosting industry or may be i am not aware of such concepts in web hosting. Are they feasible and a workable solution? Does this have any downside?