You could try posting a request in the Wanted section on here, and see what turns up. There are always plenty of alloys for sale in the For Sale section as well, and I think Jibberingloon is the resident Nutzer's wheel specialist.
You can pay as much or as little as you want really. Do you want to buy new? or will you consider 2nd hand wheels? If you like the BBS style then you may find some BMW rims in the correct size (pcd 4x100).