I am a web applications developer. I just developed a web based real estate solution targeted at firms who sells lands on installment basis. The application is web based (which means it can be accessed anywhere). It has the following features:
1. 3 User Roles: Administrator, Sales/Account Officers & Clients;
2. The Administrator has User management, Clients Managements, Reports, View Payment History for a client, view the audit trail, etc
3. The Sales/Account Officer can add client view clients payment history, make payment for a client, etc
4. The Client can view his/her payment history, make payments online, manage his/her profile, Gets SMS & E-Mail Alerts when their payments are approved.

Dont worry about the cost..........it is very affordable.

I already have a client using this application www.fruitionestate.com, You can call 08095480534 for more info.