If you are starting with kits, any of the starter packages on offer should give you the basics, you will grow your collection of stuff from there.
One thing you probably wont need is a Mercury Thermometer, the one in the link and most of those available outside laboratory suppliers are going to be Alcohol Thermometers (use alcohol rather than Hg, not for measuring Alcohol).
For kit brewing a thermometer is probably going to be less important than it is to a grain brewer where mash temperatures are really critical.
When the time comes to buy a thermometer buy a decent one, I had a look at a bundle of cheap Chinese ones, there was a 20oC spread on the readings (useless). Alla from France are widely available for less than $20, they are generally pretty good for the money (some good homebrew shops stock these or contact Winequip they have a presence in SA).
High-end laboratory thermometers can cost hundreds of dollars, I have a certified NATA calibrated thermometer that would cost over $400 to replace, only used to check other thermometers and sensors, you don't need anything like that but a decent one is a must.
Use it as a reference, plenty of electronic ones out there, problem is you don't know if its working properly or not so check it against your reference thermometer regularly.
The one thing you really do need is temperature control of your ferment. I would rate this above moving to all grain brewing, in fact above almost everything except good hygiene (Cleaning and Sterilising).
Get an old fridge, get a temperature controller, put a small fan in there for best results.
You can get a decent controller off eBay for less than $20 (search for STC 1000) if you are comfortable doing some basic wiring, or get one from your local home brew shop or a forum supporter (like, Inkbird at the top of the page).
Without temperature control its impossible to make consistently good beer all year round!
First thing is good hygiene, get a good cleaner and sanitiser, only ever clean brewing equipment with a soft cloth (abrasives will make scratches where bugs can live). There are lots of options, I use Sodium Percarbonate as my general cleaner and a peroxide based sanitiser or 70% alcohol (ethanol) in a spray bottle to sterilise . Also have a collection of other products that I use from time to time or for special jobs like yeast culturing where you need to be ridiculously careful.
If you think its clean and sterile, you are wrong, be sure!