You can't "buy a championship". At best you can buy a better chance of winning one at the cost of mortgaging a part of your future. It's not unlike an NFL team restructuring contracts to create cap space so they can afford a free agent. Yes, you can do that for a better chance to win now, but you're going to pay for that down the road.
Right on. I think people dramatically overrate the effectiveness of trying to "buy" a championship, anyway. I went back last year and calculated presumed championship odds for various teams in my leagues based on the all-play records of all the teams in the playoff field at the time the playoff starts, (which of course assumes that team strength is comparable in the playoffs to what it was in the regular season, which isn't always the case, but we're going for an approximation so I'm happy to handwave that). If you're interested,
the article is available here, and since it's last year's content, I believe it should be accessible whether you're a FBGs subscriber or not.
Anyway, the takeaway I had was that you could take the best team in the league, give him a first-round bye, and he'd still probably only be a 1-in-3 shot to win the title. I calculated the same for some of the best teams I had ever seen in my decade and a half of fantasy football, a team with an 84% all-play winning percentage, a team that outscored 2nd place by almost as much as the 2nd-place team outscored the 2nd-to-last place team, and even with the bye they were barely breaking a 50% chance at the title. So let's assume that the best team in the league decided he wanted to "buy" a title, and he somehow managed to make enough trades to turn himself from "the best team in the league" into "the best team in league history". All of those moves would improve his playoff odds by maybe 15-20%. We're talking about the equivalent of adding Jamaal Charles and Calvin Johnson and maybe even Drew Brees the day before the title game. That kind of haul improves your odds by 15-20%.
Fantasy is just noisy and messy. When you trade for a guy, there are 4 possible outcomes.
1. You win the title / you would have won even without the trade.
2. You lose the title / you would have lost even without the trade.
3. You win the title / you would have lost without the trade.
4. You lose the title / you would have won without the trade.
No matter what, scenarios 1 and 2 are by far the most common outcomes. Scenario 3 is possible... but people underrate the degree to which scenario 4 is possible, too. I've seen plenty of situations where playoff trades backfired. I saw a guy trade a 2nd rounder for a defense with a great matchup, only for the move to cost him 10 points as his regular defense blew up, (though, in fairness, that guy fell in category 2- he would have lost regardless of which defense he started).
In my opinion, the only real way to buy a championship is to call your opponent before the game and pay him money not to set a lineup.