If you've got a good trickle charger and keep your battery topped up, you shouldn't really be having to buy a new battery all the time.
There's a multitude of suggestions that would help your situation. Since the cold weather is affecting you, I first look at the carbs and a/f screws to see if they're set too lean. Otherwise, where you start depends on the condition of your bike. Peruse the forum a while it's been discussed often at great length
if you need more than what I'm suggesting below.
My suggestions on the hard starting:
1) Ignition system gone through: Better coils with removed ballast resistor (stock ones just dont cut it, even when new). New leads, plugs, connectors.
2) Thoroughly cleaned starter motor. The more efficient your starter, the more power you get to your plugs.
3) All connections checked and re-soldered if needed.
4) Clean the carbs, set idle screws set at 3-4 turns out (manual is wrong on idle setting, trust us on that one), sync the carbs. Then fine tune them if you can.
All of this is cheap to do and primarily just requires time investment to do the cleaning, rewiring and adjusting. Made a huge difference for me.