Selection is pretty poor at msystems.gr. G550M and G650M are okay, the rest are too bad quality or overpriced.
priveshop.gr has nothing interesting.
Finally at pc1.gr you have a good selection of brands at good prices. Several choices depending on how much you want to pay:
XFX TS 550 Bronze 73€ - Good no frills unit, better than CM G550M but efficiency is lower.
Seasonic M12II-620 80€ - Good unit with fully modular cables and Bronze efficiency. 80€ is a good price for this. Quality is on par with the above but overall a better deal due to modular cables and 70W more capacity. Quiet up to about 300W load, can be noisy beyond that.
Super Flower Leadex 550W 107€ - the unit EVGA 550 G2 is based on. Warranty is 5 years, EVGA offers 7.
Corsair RM550x 111€ - Comparable to EVGA G2 and SF Leadex.
XFX XTR 650W 115€ - Modular, highly efficient, very reliable. Basically an RM650x but with 2 years less warranty and noisier fan. If you don't mind those, 4€ is a very small price to pay for an extra 100 watts.
Corsair RM650x 122€ - Comparable to EVGA G2 and SF Leadex. Probably the priciest unit you should consider - it has all you could want plus extra 100w capacity.
Now that I wrote all that, I would scratch XFX units and SF Leadex off of that list. It boils down to:
want to go "cheap"? -> M12II-620
want Gold efficiency and 7 year warranty? -> RM550x or RM650x