I use to handle rentals but only handle sales now. I have been doing real estate in Alameda for over 26 years and was born here. The best bet for your sister is to work with a rental department in Alameda. It is customary for the buyer to pay 30% of one month's rent if working with a rental company. Sometimes when a company manages a property, the seller pays the 30% fee. I always refer my clients to two different rental companies in Alameda. I believe that the $30 fee is to check their credit. If they want to purchase in the future, checking their credit too many times can ding their credit. If they have questions either you or your sister can contact me for information and I can lead them in the right direction.