I'm lucky enough to get away with 3/2's for a chunk of the year. My three year old was getting frayed at the legs and the zip pull went.
Bought another exactly the same on here for 50 quid (cheers lecky94), minter, hardly used and now ring the changes. Having two seems to really prolong the lifespan of both
PLUS, I have a couple of water butts and rinse EVERYTIME
after a surf. The suit then has at least 24hrs to dry, never in full sun.
PLUS, PLUS, I get changed at the beach standing in a large plastic garden trug thingy so they never touch the sand/ground/carpark/dogshit whatever.
Bottom line, you spent a lot of dosh on the second most important thing, look after it as you would your board.