Am I selfish?

My boyfriend and I have been talking about getting engaged and the other day he told me to go online and start looking at rings and give him a few options. I said "okay so what's my price limit? Like $3,000?" He looks at me and says "I make enough money, there is no limit, pick whatever you want." I was in shock and said "so if I find a $50,000 ring I like I can have it?" He said yes if that's the one I really want. Now of course I couldn't fathom him paying that much for a ring but I did look and I found one I fell inlove with. But I don't want to show him it because I KNOW he will buy it. Now I know I don't have a price limit but is it selfish of me to ask for a $18,000 ring???
EDIT: my boyfriend makes $160 an hour, works 18 hrs a day 5 days a week and has been at this job for 5 years. You do the math. He can most certainly afford it and anything else
EDIT2: my promise ring was $7000. He has also bought us matching 2006 dodge Cummins tucks (I paid for my own but he put the down payment on it). Own our own house (that means we don't have a mortgage, paid for it in cash) He is a bit of a tight ass on most things and saves 80% of whatever he makes. We also raise cattle.