For a case study I have to work on for a university course, about a real-estate-development project, I need to simulate the financing with different proportions of equity (40%), senior loan (35%), junior loan (15%) (both from banks), and mezzanine financing (10%) (over 5 years, starting now). I tried to do research, mostly on the net, but did not find any credible sources. Can you give a hint where this can be found (I only need approximate values, to have an estimate)? Is there some national or international index or something similar?
The answer to this is, unfortunately, not straightforward due to the number of moving parts and no strong reference point.
These types of interest rates can vary highly -- which, during the course of your studies, you will discover is partly a function of the risk-free rate and the risk-premium the project attracts with respect to similar projects. There is also a high degree of variability with respect to the real-estate developer's perceived credit risk.
You can certainly back out much of the data you need using Aswath Damodaran's corporate finance database under the "Updated Data" tab:
By point of reference, Senior Secureds generally represent 1x Assets or EV. Senior subs about 4-5x and Jnr Subs around 7-8x.
What you really want to find is the spread these products currently have over LIBOR. As you're a student, you should be able to get access to Bloomberg where you can use the
Failing that you could try ValueLine - your school will almost certainly have a subscription - and again back out the implied rates.
As a last ditch attempt, use the implied rates priced into ETFs of corporate bonds of differing grades. BarCap has quite a few of these listed in the US.