the HKS Racing Chamber kit is reasonably priced, the Trust is as well. But it's all relative as they are 75,000 and 99,000 JPY respectively (499 GBP-660 GBP). They are full suction kits replacing all the piping before the intercooler.
If you are looking for a simple pre-MAF filter and elbow kit the Apexi is the best IMO. It's priced around 30,000 JPY (199 GBP) and has some of the best filtration and performance characteristics.