Considering neither will be quality, in that case you are paying for more wattage and a name.
The difference between a quality PSU and non is the parts. Efficiency and overload make a difference, and typically crap units are underrated and can't actually push the amount of watts they are rated for.
A good PSU will hold up for years, will not drop 12v under load, and can actually push more watts than they are rated for. It's not recommended, but it's very possible.
A lower quality PSU will be made of cheap materials that can pop under strain, die for no reason, or not hold up to a mild load for extended periods of time. For instance, I would not try to pull 525w from that Cooler Master for more than 10 minutes or so.
Since the PSU is feeding electricity to very sensitive electronics at all times if it dies it can take your whole computer out at the same time, or if you are playing a game and the 12v voltage drops too low it can fry your video card or CPU.
Hope that gives a little insight to why having a decent PSU makes a big difference.
Since the 7750 only consumes around 45w max you don't have to worry about a high wattage unit as the i3 is only 55w. In theory, a nice 350w unit would be perfectly fine but if you are dropping money on a PSU you might as well make it a little more than you need so you have room to upgrade later on.
If you can afford it, I recommend getting at least this, or a Corsair CX500. Gives you room to breath and you can put something as high as a 660ti or 7870 on it.
SeaSonic S12II 520 Bronze 520W ATX12V V2.3 / EPS 12V V2.91 80 PLUS BRONZE Certified Active PFC Power Supply - Newegg.com
If you can't afford that, then I would at least get this.
CORSAIR Builder Series CX430 430W ATX12V v2.3 80 PLUS BRONZE Certified Active PFC Power Supply - Newegg.com