R4i – R4 DSi Buyers Advice
Nintendo’s new console may come with its own built in card reader, but unfortunately it’s very limited it what it lets you do. You can’t play mp3 files or run homebrew software for example. The good news is that you can unlock the ability to do just about anything with your new console for a fraction of the cost of the DSi. R4 is now available on your new system.
When you are looking for a R4 DSi (R4i to give it its proper name), you are likely to come across a few fakes that are being sold for a cheaper price. Buying these units usually isn’t going to cause any problems but some claim that it may leave you with a strange clone that doesn’t have all the features that you wanted to enjoy. With first party accessories it is easy to spot if they are real simply by looking for the Nintendo Logo.
However, things can become more challenging with 3rd party accessory made by small business; particularly the new R4 Revolution DSi. As with the original R4, the R4dsi is not a Nintendo made accessory so it can be difficult to tell what are real. What you need to understand is that the R4 Nintendo DSi version is indeed a real device that can really run homebrew software on the SD card and a number of other file formats. What makes it more difficult is that a large number of clones are copying the R4 for DSi as well. Since it is harder to find in stores, getting the real deal could be tough. But it is still possible to get one if you follow these steps in separating all of the fakes from the actual products.

I WANT A R4IDS
Where can I get a R4i for a NDSi in UK
Have a look here http://www.r4revolutionds.co.uk/r4-where-is-it-safe-to-buy/