i've been playing for about 3 years (give or take)
never coined
i just took a look at the items i haven't used and added up the top 10, based on individual value
they added up to 14700 cents, that's a little more than 600 x 24 cents
i also won about 1800 cents, a bunch of on-wars and speed ups

think it's pretty safe to say that 24 cent average is conservative

i do love the wheel, even the quarry tools and plowshares i use to time my cooldowns