Is the such a thing? ie. something that matches it on price and performance?
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I loved my 550D/50mm f/1.8 setup, so looking to replicate that in something a little more compact. It doesn't even have to be M43rds if there are other options.
Are you particularly wedded to the field of view you get with a 50mm on the Canon? If so, you would need a (50*1.60) / 2 = 40mm to get the equivalent FoV on (micro) Four Thirds.
There aren't many 40mm lenses around and none designed specifically for the m4/3 system. However, if you are happy with manual focus, you could try the original Pentax 40mm/2.8 pancake. Not the current DA Limited one, but the original M lens. You will be able to get one, with a K-mount to m4/3 adaptor for under £100.
It was never the greatest lens as it was designed for compactness and affordability rather than sharpness (for that you want the 50mm/1.4) but it should make a fine lens on a compact m4/3 body. There's a review
here. I intend to give this a go when I get around to buying the K-m4/3 adaptor.
You could also look at the manual focus Voigtlander 40mm Ultron which is faster (f2) but 3-4 times the price.
If you don't mind something a little longer, the Olympus 45/1.8 is reported to be a very fine lens indeed. It would be more like a 90mm-equivalent than your 80mm-equivalent fifty on the Canon.
I can highly recommend the Olympus E-PL3 for the money. If you get it before end of Feb, you can get it body only for £279 after cashback, which is an absolute steal!
Personally, I'm going to get the Lumix 20/1.7 as the 40mm-equivalent is just perfect for me (I also use the Pentax 43mm on my film bodies).
You could look at the Sony NEX system too, but it has the same size sensor as your Canon and although the bodies are generally very compact, the lenses tend to be bulkier and heavier than Micro Four Thirds.
Oh, and if you (like me) find it difficult working without a viewfinder, you should wait a couple of weeks to see what the rumoured Olympus OM-D will be like.
Ultimately if you're buying a prime lens, it depends what you're shooting.