Buy the best you can afford...and don't be tempted by cheaper stuff that may appear to be good value at the time!...You will regret it!..and remember the base layers are at least as important especially in the Colder months!
A lot of the top Brands like Musto,Henry Lloyd,Gil ect can be bought with really great discounts at Retail outlet parks.. and always ask the manager if there are any special deals..The good stuff is not always on the shelves
I bought a worn once Musto HPX on eBay for my wife on eBay for £120!...retailing over 1k!(wish it had been my size!) so there really is no reason to buy rubbish.
I'd concour with others about the need for good washing and I also use a (small) amount of silicon grease on zips/fasteners/Ghecko poppers to help stop corrosion which works well.
I like to hang ALL Waterproof garments rather than fold them up or use stuff bags as I've seen some do...the waterproofing will defiantly last longer.
I've also found the more recognised Brands have excellent returns/warranty policy's.
There's a little known Ocean going racing site called "Fierce Turtle" where a lot of low use ...High Quality Sailing gear pops up which is worth a look.