Depends on what items you buy and how many you cram in there. You can get some GC-themed furniture from your GC too with Company Seals/Allied Notes so that's always an alternative to just buying stuff from the Market Board. The Housing Vendor in each housing ward also sells some furniture as well (often cheaper than the MB!) so that's another option too.

But yes, as Blindheart said, if you can craft your own furniture it will probably turn out cheaper than just IKEAing it.