I just rode into work wearing a pair of ex British Army gore tex overtrousers. They are great, cheap keep you dry and keep all the cack of your good riding pants.
They offer weather protection but no impact/abrasion. They last a good while, I make sure they fit over other pants so that they dont ride up and I wear highish boots.
I have used similar including some ex Dutch Army salopetes and have always been happy with how versitile they are.
I am not sure I would use them in the tropics but then to have strapped to the bike as a wind/water proof layer they work just fine.
I have also used them to snowboard in etc and they work fine for that over other ski pants or thermals.
I also have some very long gore tex over mitts, these cost £5 and work great in heavy rain/cold weather to cover my gloves. again they are cheap and roll up small and stop you getting wet and cold. They replaced a pair of gore tex climbing mitts that cost more than 10 times as much and there is absolutelty no difference in quality.
As long as you don't mind the camo look ex army gear can be cheep and cheerful and lasts a good while. (be careful where you buy it some places rip you off)
A vented protective jacket and trouser combo with a gore tex jacket and trouser cover would not cost much and would provide all the protection any one would need for many different climates. just layer up underneath and you can stay warm and dry and not sweaty. Think of this a cheap alternative to a KLIM suit and you can be on route for about £200 max
My set up cost me less than £100 but I was lucky to get an airflow jacket and pants for £50 from a bike show and the gore tex jacket/trousers and mitts for less than £50 as I have a great surplus dealer just across the way.
Try RTI Military Surplus - Wholesale Army / Military Surplus
these guys are cheap have a massive stock and public showroom just off the M1 at Junction 20