I would select Arca-Swiss over Technicas for architectural photography, especially iv or v. (Not very wide-angle friendly, especially below 90mm.)
EBay frequently has Arca Swiss up on auction. Or, Midwest Photo Exchange, Photomark in Phoenix, Badger, or Quality Camera. For information from people who are Arca Swiss enthusiasts, call Photomark or Badger. If you go ebay, make sure that the seller has at least 100 feedback entries (personal opinion), and no negative feedback within the last 6 months.
www.badgergraphic.com www.mppx.com www.photomark.com www.qualitycamera.com www.ebay.com