I mean, if you're going to go to the damned Home Run Derby, you may as well catch a home run ball, right? Here's where to sit if you want to catch one—and where the most cost-effective seats per home run happen to be.
SeatGeek made the tool which output the chart you see above. It plots the regular season home run locations of each player as they'd have fallen in Target Field and then scales it against the likely number of home runs hit in a Home Run Derby. You can toggle between individual batters, which shows you stuff like, "If you want a Giancarlo Stanton ball, you should probably be in the upper decks." But more broadly, if you toggle everyone on at once, it'll show you where the best bet for catching a ball at all is.
From the look of things, that would be section 229, which saw 12 home runs hit to it by the batters this season, and is in line for an expected 8.15 tonight. Section 128 had 13 and is set up for 8.83 tonight, but it's also a bigger section. By cost, the best you're going to get is section 238. You can futz around with the tool yourself here.