I would suggest you look at Renishaw: try this site - http://www.renishaw.com/en/carbon--8269

you can try also

http://www.horiba.com/in/scientific/products/raman-spectroscopy/raman-spectrometers/raman-microscopes/

T64000 Triple Raman Spectrometer - HORIBA

I have used both Renishaw and Labram HR from Horiba. I personally prefer Horiba as it can provide u with much higher resolution. However, Renishaw is more user friendly. Quite frankly, for normal every day use, it really doesn't matter which type of equipment you use. Because  you can get decent answers from any kind of Raman measurement system. However, if you really need to perform a full characterization, you need to have a system with at least three stable laser systems and a high resolution detector.

I think the type of instrument is not issue here. The main point is spectral coverage. Try to find the band at 44 cm-1 to characterize your graphene. 

I can propose You the following solution: a "Nanofinder HE" confocal Raman/PL spectrometer  (LOTIS-TII, http://www.lotis-tii.com/eng/productid81.php).

From my viewpoint, this setup has the following advantages:

1. You can choose one from 4 lasers for the sample excitation;

2. Yoy can choose one from 3 diffraction gratings with the best spectral resolution

of appr. 0.3 cm-1;

3. You can change the excitation power in very wide range (several orders of magnitude) to avoid a sample damage;

4. High-quality CCD  detector is used providing a low background signal and high sensitivity;

5. There is a system of automated spectral calibration.

What you would like to have is the ability to perform :

1. low frequency measurments for the