Legacy Cumulus 1 release 1.9.4 (build 1099) - 28 November 2014
(a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)
Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki
That model does NOT have a wind direction vane (so no top "T" bracket), nor a PC interface, nor AFAIK even a Logger. So it's really rather expensive compared with the £50 - £60 that the "full" versions are sometimes available for.
Note that the transmitter (ext. temp./hygrometer) is NOT compatible with the full units (the wind direction is missing from the data protocol), nor of course is the Console. A spare transmitter for the N25FR is £10 whilst that for the N96FY/N96GY is £15.
So, unless you need the "mechanical" bits (mast, sunshield, brackets), the only useful "spares" are the anemometer (various model numbers but all electrically compatible, and only £2.50 as a spare part) and the rain gauge (also normally available as a spare for £10). The vane is one of the more complex parts, but also available for £10 as a spare part (if in stock). Some shops even keep the spares in stock, but they can usually be "click and collected" for free if you have a local store.