Flats are simply a part of riding. You can minimize but never totally prevent. I dislike slimed tubes since you cannot patch them when they get a puncture too big for the sealant. And they WILL get one too big.
I run extra thick thorn resistant tubes and have been doing real good so far this season with only one nail which took about 5 min to patch. I don't even remove the rim usually anymore unless there is serious damage.
Tire liners are another layer of protection and with thick tubes, will stop 90% of punctures. By using non-slime tubes, you can easily patch that remaining 10%.
Except for the really bad ones...
which nothing will stop.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.