The Mishna and Gemara discuss that the Sons of the Cohanim Gedolim (presumably a phrase including their supporters and family) would pay from their own money to construct a new ramp for the procession of the Red Heifer. This was a rare occasion that perhaps a High Priest did once in an entire career, though Shimon HaTzaddik who had a long career, actually oversaw two Red Heifer rituals and paid for a brand new ramp for each one.
The Gemara observed that these construction projects were ostentatious, costing 60 gold coins. At first the Gemara is critical, considering this conspicuous consumption as coming from brazen arrogance. However, noting that Shimon HaTzaddik did the very same thing led them to a different conclusion. Ultimately, out of high regard for the mitzvah, it was permitted to make such grand and lavish expenditures.
There is an interesting responsum from Chasam Sofer (שו״ת חתם סופר יוײד ר״כ ) Regarding a city council building that was dedicated by an oath that no subsequent party or ruling group would be allowed to sell it or switch locations except under extreme duress such as being driven into exile. Under circumstances that were less pressing, a new governing group wanted to change the building. The Chasam Sofer ruled that it was not permissible, offering a number of reasons, including quoting this section from our Gemara that it is morally reprehensible and wasteful to deconstruct what others have built in order to establish political dominance.
Apparently, Chasam Sofer felt that the Gemara did not fully retract its condemnation of the high priests for their lavish expenditures. It would seem that if these actions were politically motivated, then overspending and ostentatious displays of power and wealth was considered reprehensible. Indeed, during the second temple the priesthood was intertwined with political influence and bribery (See Mishna Yoma 1:1 and commentaries on phrase Lishkas Palhedrin). Yet, on the other hand, spending large sums to honor a rare mitzvah, such as Parah Adumah, is considered exemplary.
In terms of our own financial ethics, it would be up to us to determine when we spend money on grand events such as weddings, bar mitzvahs, inaugurating a Shul or Sefer Torah, which category does this kind of spending fit into?
Translations Courtesy of Sefaria