I am trying to move away from the DL180 discussion, as per my previous post:
Perhaps you missed my comment on the H310 HBA? The H200 or indeed the IBM branded version is equally suitable and all are £25-40. If you want a rack mount then the SC846 is a decent shout and the 2U version will do 8-12 drives, just be careful the backplane fitted suits your needs (6G for 2TB+). Silverstone aren't cheap, but they tend to be high quality consumer grade hardware. I'd suggest considering what you actually want to get out of this before going further.