New Image don't apologise. You don't need to justify yourself, it's your money. As you said, $200 is a lot of money (for me too by the way). Me personally? If a store I like and has given me good service over the years was only 5-10% more expensive then I'd stick with 'my store' for loyalty sake. When we're talking such an enormous difference though it's not about loyalty.
The comments about "scratch and claw" are largely irrelevant here (although that too is subjective) as you weren't talking about going somewhere else for the sake of $10, we're talking $200. I WISH I was in a position where I could afford not to care about $2000, sadly I'm a lowly government employee so I need to watch my spending.
I also don't understand using phrases like "leave you" for another store. Sorry, did you exchange rings with AG? If you're in serious relationship it's a different story. You should really man up and tell them in person that you're buying from someone different. Don't do it in email or text message, that's for cowards.
