I would it depends, but yes, you can base your entire business on referrals. I'd suggest formalizing your plan, being transparent with the realtors, and providing an exceptional experience to the prospects so the realtor feels good about recommending you in the future.
- formalize how you ask them (recommendation might sound better than referral)
- formalize fee structure, or what you'll pay them (e.g. 10% of what?)
- share with realtor your process and how you take care of the prospect to gain confidence
- your realtors now become your sales force. Take good care of them, train them, show them the opportunity, and stay in consistent contact with them
- also, create a formal (or informal) training program for your realtors so they use the right words, descriptions in talking about you
- have a good website that the realtor can tell the prospect as they'll probably want to check you out.
- finally, address how the realtor can ensure they'll get paid and you will 'forget' about the recommendation.