First off, Simtec seem to be having a clear out with four 2MB VRAM upgrades for the Risc PC going for 50UKP each. These are brand new modules from their "reserved stock". They also have an A4 laptop which appears to be in mint condition with a larger than usual hard disc, and a brand new battery pack. A4s commonly have problems with dud battery packs. This auction also includes all the original packaging, and documentation.
govind_uk is selling a RiscStation 7500 computer which is currently at 5.51 UKP. The machine has a pretty basic specification with RISC OS 4.03, a 4GB disc, and 48MB RAM.
Aaron Timbrell of Virtual Acorn fame is selling his spare four slot back plane for a Risc PC. These are useful if you have more than one slice in your Risc PC, and want to have more than two podules.
Finally, although our friends over at the launchpad seem to have taken up a vow of silence, editor Peter Naulls is selling off various hardware from an ex-Acorn employee. Listing it all here would take up too much space, so read his comp.sys.acorn post. He is not willing to post the hardware, so you'll have to either collect from him in Cambridge, or at the forthcoming SW show.