jmercier, welcome to the Forum and congratulations on your new i-MiEV!
The answer to your question depends somewhat on the type of power available in the vicinity of your car parking location.
First off, to get you started, you will find that the Mitsubishi EVSE that comes with the car will initially be adequate - simply plug it in in the evening and you will have a fully charged car in the morning, good for about 50 miles (80km) with no worries. Do not be concerned, as, unless your situation is unusual, this distance is sufficient for most people's daily driving needs. If you drive consistently you will find the car's Range Remaining indicator quite accurate, and you will quickly learn exactly what your various typical driving distances are. If marginal, simply slow down!
There are a number of good reasons for obtaining a Level 2 (L2 - 240vac input) EVSE; for example, there are times when you may need to recharge at home during the day and would like to do it faster than Level 1 (L1). The recharge rate using L1 (12A setting on the Mitsu EVSE) is about 9km/rechargehour vs. about 20km/recharge hour using L2. The first decision is whether to keep the EVSE as a portable (or transportable) unit vs. a permanent installation.
A permanent installation results in a slightly-less-cluttered appearance, but otherwise offers little advantage (IMO) over a portable unit; however, it might be required by local codes. For myself, I have located a 240vac outlet (NEMA L6-30R) right next to where my EVSE is mounted and I simply have the male connector on the end of the EVSE input wire which plugs into that outlet. My EVSE (an older SPX Power Xpress, now marketed by Bosch) came with a nice bracket that allows me to remove the EVSE instantly.
For the i-MiEV, a 20A circuit and EVSE are sufficient since the i-MiEV draws less than 13A at 240vac, and thus, for example, a NEMA L6-20 plug and receptacle are sufficient; however, as part of this initial purchase, for future expansion you might consider both a higher-capacity circuit as well as EVSE since almost all BEVs going forward will undoubtedly have larger onboard chargers.
Incidentally, if you will be installing an EVSE in your garage, consider parking the i-MiEV against the right wall and putting the EVSE on that right wall just inside the garage door. This will allow you to only unwind maybe a metre of cable in order to charge (keeping everything nice and clean and quick), and also gives you the option of pulling out the cord to charge a car outside.
To answer your question,
sandange has given you a number of good leads - the EVSE is a pretty dumb device and they all work, so price is probably a significant factor in your choice. My own preference is for the relatively-low-cost (here in US) Clipper Creek units
http://www.clippercreek.com/products.html , simply because they provided me with a free much-needed charge at their Auburn facility during my long Christmas Day road trip last year. :roll:
All the best to you, and hope you get to enjoy your i-MiEV fully before winter hits!