If your beer is good, upgrade your system to meet other goals (volume, safety, temp control), if not, work on your procedure with the equipment you got....unless that equipment is hampering good beer (such as infected plastic fermenters and transfer tubing).
You can make good beer without exacting temperature control, btw....just don't expect to make a light lager or other very temp sensitive beers....if you have 78 degrees, make a damn good saison....but more likely, find a cooler place in the house to ferment and lager.
I suggest making the best beer you can with what you have....and then decide what your limitations are and design upgrades to solve for one at a time. It is a bad practice to say temperature control is more important than sanitation....IMHO. There is no substitute for (nor any excuse for not having) good sanitation practices. I like upgrades that make my brewday easier and safer as well as eliminate mistakes and breakdowns....when you upgrade, I like durability...buy it to last.
Unless you are made of money, that is, then just go buy the best out of the gate....it won't make you brew better, but you won't be able to blame your equipment if things go awry.