ive been keeping an eye on german ebay lately as i want another set of h&r springs to change the eibachs on my m3, it seems to be best place to get the likes of h&r or eibach springs, i got my bilstien shocks from there at a great price and very quick delivery, ego autosport was the company.
from my research and expirence with both eibach and h&r springs (on m3's), eibach are more softer/comfy spring with a moderate bit of lowering where the h&r is slightly stiffer with a tad more lowering than eibach, but this might not apply to an f10