Since Benjamin Šeško wants to play for Manchester United, I believe Manchester United and Leipzig will agree on a transfer fee for Benjamin Šeško because Manchester United can't afford to start the upcoming Premier League season without a quality striker that could help them improve their performance and have a chance of finishing in a UEFA Champions League spot next season. We all know that Manchester United isn't a Premier League title contender for next season, but if Ruben Amorim succeeds in bringing in Benjamin Šeško and Morten Hjulmand to the Theatre of Dreams, Manchester United can surprisingly become a Premier League title contender.
As long as Šeško has the intention to join Man United, I agree that Man United probably will successfully sign him. Besides Man United is in urgent to have a more quality striker, they are also a club that often buy a play with expensive price. They even could sign a player overprice. So, I no doubt with Man United to deal with the minimum price expected by Leipzig. 
Dude, it is too early to expect Man United achieving the UCL zone or winning the EPL trophy. TBH, I don't underestimate Man United. However, considering the quality of their current squad and their performance in the previous season, I totally doubt that they will finish in the season in the top 5. I just expect that Man United to return to the top 10. It is the reasonable target that they can achieve in this season.