Pretty silly idea in NBA. The closest a team ever came to buying a title was LA with Malone and Payton -- and they lost! With the cap and trade rules in the NBA, you can't buy championships. Pretty much baseball only is the sport where championships are bought.
We traded assets. This is nothing new. Denver traded assets for Iverson, Dallas traded for Kidd, LA traded for Gasol, Phx traded for Shaq.
The only difference between the Celtics and Detroit is that we traded for 2 of our starters in 1 offseason, while Detroit picking up Wallace, Rip, Billups, and BWallace happened over many seasons.
Considering NONE of our starters were picked up as free agents, the "title buying" theory is nonsense.