Don't use your line for it. Use your wife's line.
One of my lines will be eligible around the 25th of that month. I couldn't wait.
Edit: I just opened a line and still used it as an early upgrade to the 4s. If you use it on your line, you'll pay the same price you would upgrading your wife's again (if the system allows you to).
Thanks for the suggestion Duvi, but no go. My wife's line was eligible for an upgrade from her 3GS. Her battery is not lasting that long now so she badly needs a new iPhone. I have decided to wait until November when I am eligible, and I already have the money saved up. I'll just enjoy my 4 for a little while longer. The only thing that makes me mad is that when I checked my eligibility a few months ago AT&T said I only had to pay the upgrade fee. Then when I checked it after Apple announce the pre-order date suddenly I have to pay an extra $250 plus the upgrade fee.
Although, I still get that itchy feeling to pay full price anyway!