Carpet cleaning essentials excluding CC machine and obvious attachments): -
ProchemFibre and Fabric Rinse
Prespray Gold
Multipro
Ultrapac Renovate
Powerburst
Odour Fresh
Liquid Defoamer
Citra-Boost
Filterout
Oxibrite
Gluespot
The stain kit (speak to Vicol who sell at about £120 from memory). Also keep a stain guide for reference and if it helps take your training manuals for reference.
Kit (minimum requirement)Sebo BS36
Pump up sprayers x 2
Envirodri, including at least two sets of brushes (white / gold - wool, black / white - synth)
20 metres min of hose.
Turbo dryers min 2
Furniture Sliders
Furniture pads
Grooming brush / rake
White towels
white kitchen roll
buckets x 3
2 litre jugs
1 litre jugs
Variety of smaller brushes, tamping etc.
Gloves
There are a few other bits and pieces such as PH testing kit, waterproof dust sheets, clear tarp for covering the CC when left outside in the rain, small extra thick tarp for putting under the CC when located inside the property being cleaned, measuring scoops, spare fuses, the list does go on and no doubt I've missed something obvious :

Although I mainly use Prochem and so consider the list above as my essentials I also have a few Alltec chems, Ultimate Master being about as easy to use as anything (as long as thoroughly mixed before adding to tank). I am just about to have a dabble with M-Power from Solutions as I tried some of their Fusion Clean recently and was very impressed.