Soon after Illumina announced its HiSeq 2000, it also announced the GA IIx's little brother, the GA IIe. The IIe will produce about half as much data as the IIx, but no one seems to know exactly how this is done. The unit is cheaper than the IIx, $250,000 for the IIe compared to $400,000 (I think) for the IIx, but is upgradeable to the IIx. So perhaps the optics system is cheaper. But the run time is the same, so it seems like the optics would need to be about the same (the older optics system was slower). The IIe seems to use the same kits as the GA IIx. That seems odd to me because the consumables cost is typically the largest part of the per run cost. So while you will save on instrument depreciation costs per run, those savings disappear when considering cost per Gb. Another way to look at it is that if reagent costs are indeed the same, it makes no sense to buy two GA IIe instruments. You would be much better off buying one GA IIx. It is only if your lab has a sequencing workload that cannot utilize a GA IIx full time that a GA IIe makes economic sense.