Hi Clint,
Lowlanders like N. ampullaria must have temps between 80-90*F during the day and 70-75*F and humidity 80% or higher to grow and pitcher well.
Highlanders such as N. hamata and N. rajah must have temps between 70-80*F during the day and down to 50*F at night to maintain steady growth and pitchering. Highland species are also more particular about airflow (they need it-lowlanders don't require it). Humidity must also be higher for highlanders (90%+) than required for lowlanders.
Before jumping into expensive highland Neps why not try the somewhat cheaper and easier lowlanders to kinda "cut your teeth" on experience. The highland plants will still be available in a year or two and will possibly be cheaper than they are now. Once you've grown lowlanders try some of the more forgiving highlanders like N. sanguinea, N. burbidgeae, etc. These guys will tolerate less than ideal nightime cooling. If you are determined to go for higlanders it is best to design an automatic system to provide nighttime cooling. My website will soon have an article on how I built my highland chambers cooling aparatus.
I want to state that I do not believe in the ice chest or frozen water bottle method of night time cooling. This is a very temporary solution to a problem that will plague you for the life of your plant. The ice chest or frozen water bottle method will only work while they are very small and in a very small enclosure. The condensation formed on the water bottles at night may actually pull the humidity out of the air at night. Highland Neps don't like cool dry air any more than they like warm humid air. Also the less your plants are shuttled from one place to another and left in stable conditions the faster they will grow.
I should mention that contrary to popular belief, these two highland species do not really grow slowly when grown in proper conditions. My N. hamata has gone from a 4" diameter seedling to an 18" diameter, 2 ft tall climbing plant in under 18 months. My N. rajah has also gone from 2" diameter to 18" diameter in 18 months as well it has produced 7 offshoots 4 last December-Feb and 3 so far this fall (I have not divided these from the mother plant yet this year).
I hate to keep promoting it but since you're new to neps please take a look at my sites cultivation info and FAQs:
Nepenthes Cultivation Tips It's not gospel but it's detailed info on how I cultivate my highland and lowland plants.
I hope that helps some!