go for olympus OM 28 f2.8.........

I just bought a soligor c/d 28mm 2.8 of ebay. Not sure if its good but it was cheap and the limited research i did says that its above average lens

Anyone know anything about it? i'll post a pic.

the 24 2.8 pentax auto 110 is the size of a bottle cap , literally yet it covers the image circle of the ep1 with absolutely no vignetting or light falloff, it only has one apeture 2.8 but you can make black paper disks  with holes to put behind the lens to stop it down , a five dollar body cap drilled a washer or two , an infinity focus check and some crazy glue  and you will have a nice lens thats about a 46mm equiv fov  if you get 2 and extend the lens away from the sensor you can make an incredible dedicated macro [ losing infinity focus however ] as well they are on e bay all the time for very little money the body caps in the usa are about 5 dollars each , its a fun worthwile project you can have both lenses. and when you see the cost and  results , one you will not regret
both lenses,a normal and dedicated macro, with dedicated conversions will cost  less than the cost of a single 28 slr vintage 2.8
the 28 i use on the ep1 is a voigtlander is a 28 1.9 screw mount with voigtlander m to m4\3 adapter , its not super sharp wide open, but quite useable. If stopped down to f4.  its excellent . its not in production for a few years now , having been replaced by a  M mount 28 f2.0[ said to be optically better ], but it pops up on ebay now and then  

the 1.9 is the fastest 28 rangefinder lens in history, rangefinder lenses are better suited to the ep1 because the designs are  made without having to allow for a mirror box