It can be noticeable depending on your build. I have an all well-fitted build and the difference between 28% (all purple) cost reduction and 35% (all gold) cost reduction is quite noticeable.
Weapons make a big difference, you should always get them gold.
Armour and jewellery not as much difference. You'll get a bonus of course, but you'll gain more from practice and growing player skill than those stat boosts will give.
Some jewelry traits (any % modificators) do have significant improvements comparing purple to gold - stats not so much.
<Noricum>
I live. I die. I live again.
Derra - DC - Sorc - AvA 50
Derrah - EP - Sorc - AvA 50
Level your crafting skills and do some writs. You’ll soon have plenty of tempers to gold out everything except jewelry, unless you just have to have that one extra thing to blame your loss on (“I knew I should’ve golded my gloves!”)