A:Answer In Store Only
Galaxy S9 you get $50 off, over 24 month period, unless you ordered it the first day off of the offer. If you preordered on the first day you will get $100 over a w4 month period. Now, if you pre-order in store you get, over a 24 month period, $50 off on Galaxy S9 and $100 off Galaxy S9+.
If you are doing it with a Verizon Plan you will also get an additional $350 off if you Trade In a Galaxy S8 or Galaxy S8+. Lesser phones will get you less money. Check out the Trade In price on Best Buy eligibility list online.
Verizon Customers
I suggest you Pre-order in store and opt to have the new Galaxy S9 or Galaxy S9+ shipped to you or an address you feel safe having it delivered. Absolutely no reason to wait on line at store on release day when you can have it shipped to you and will arrive on the release date.
In the box it was shipped will be a prepaid return label. You place your Trade In in the box and it will go directly back to Verizon. If the phone is in good condition (not cracked or water damaged) you can get up to $450 back which means you are getting $350 from Verizon (done over 24 months) plus Verizon will add another $50-$100 (over 24 months) if you pre-ordered at Best Buy.