Tomorrow, Best Buy will reboot its “free iPhone 5” with iPhone 4 or iPhone 4S trade-in campaign. Best Buy ran this special for one-day earlier this month, and the company said that that day was its most successful device trade-in day ever. Here’s how the program works:

  • – Best Buy will offer you $150 minimum for an iPhone 4S in “Good” condition.
  • – An iPhone 5 on-contract costs $199, but Best Buy currently offers a separate $50 off iPhone 5 campaign, so, before taxes and such, these programs combined can yield about $200 off of an iPhone 5 purchase.

The program will launch in stores tomorrow, but the company will begin heavily promoting it in its Sunday ads. The special will run for 9 days after tomorrow. It just so happens that Best Buy’s currently running $50 iPhone 5 special runs until June 29th as well.

The program does have some caveats:

  • Only Verizon, AT&T, and Sprint iPhones are covered (no T-Mobile)
  • The specials are exclusive to Best Buy retail stores
  • If your phone is worth more than $150, the difference will be applied to a gift card, not a higher-end iPhone 5 model.

Best Buy offers an online-version of its trade-in-value-checker, which could be worth trying out tomorrow before heading into a store.

Apple is also rumored to launch its own iPhone-trade-in-program later this month, so it could be worth waiting to see the details for that.