Just initiated an exchange of my Classic Buckle for a Milanese - already purchased a Black Leather Loop Separately.
Out of curiosity I asked if I could exchange for a Steel Link Bracelet and pay the difference and they said yes. They basically charge your card for the new band you are getting, then refund it for the band you send in. So for example, if I wanted I could have done this and would have been charged $449 when the Steel Link Bracelet was sent out, and refunded $149 when I sent in my Black Classic Buckle. I didn't do this of course, but the option is there!
Out of curiosity I asked if I could exchange for a Steel Link Bracelet and pay the difference and they said yes. They basically charge your card for the new band you are getting, then refund it for the band you send in. So for example, if I wanted I could have done this and would have been charged $449 when the Steel Link Bracelet was sent out, and refunded $149 when I sent in my Black Classic Buckle. I didn't do this of course, but the option is there!