I've found some capacitors that will meet your needs from RS Components - about £10 with free delivery tomorrow - Panasonic EEUFR0J332L
Some notes of Aluminum Electrolytic Capacitors (using the bad capacitors in your Xbox as an example)-
Nichicon - Brand
Nichicon is a quality and well-known brand of capacitors. Other good capacitor manufacturers include Elna, Nippon Chemi-Con/United Chemi-Con, Panasonic, Rubycon, and Wurth Elektronik.
HM - Series
The capacitor series is like a model name. It gives you the typical characteristics of capacitors in that series e.g. Standard, Low, or Ultra Low ESR, amount of ripple current capability, and temperature rating
Note: From 2000 to 2010, there were a few series of capacitors with a flawed electrolyte formula. This would cause the capacitors to fail eventually, especially when exposed to more intense heat. The bad capacitors from major manufacturers were Nichicon HM and HN series, Rubycon MBZ and MCZ series, and United Chemi-Con KZG and KZJ series
3300 µF (sometimes written as uF) - Capacitance
This tells you how much energy the capacitor can hold. If you are not sure how the circuit works, it is best to replace the capacitor(s) with those of the same capacitance
6.3V - Voltage Rating
This tells you the voltage that the capacitor can handle in a circuit. You can replace capacitors with those of a same or higher voltage rating. Just make sure the capacitor will still fit in your piece of electronics.
ESR (Equivalent Series Resistance) / Impedance
All Aluminum Electrolytic Capacitors have a certain amount of ESR in them - think of it as a resistor attached to the capacitor. Using a datasheet, you can take a look at the ESR or Impedance of a capacitor. If the capacitor is a "standard" capacitor, you should replace it with another "standard' capacitor. If the capacitor is a "Low ESR" or "Ultra Low ESR" capacitor, you will want to find a capacitor with a very similar, same, or lower ESR.
Ripple Current Capability
The Ripple Current capability (usually denoted as ripple current or R.C. on datasheets) tells us how much ripple current the capacitor is designed to be able to handle. This should be the second thing you look for after ESR / Impedance
You can find datasheets from Electronic Components Suppliers or from the manufacturer's website (A list of capacitor manufacturers' websites can be found here or here or here). You can also find some capacitor datasheets on the Badcaps Forum.
You can find a compilation of the different series available from the top capacitor manufacturers here (under Capacitor Series>Aluminum Electrolytic)