If you already had an existing Quadra, it probably made a huge amount of sense to upgrade it, financially, even if it was going ot end up slower than a 6200 or slower than a particularly fast 7100 or 8100.
The cheapest of the x200 PPCs I can think of off hand is around $1900 for the Power Macintosh 5200/75LC, which was a pretty bare-bones configuration, basically meant to be sold to educational institutions that already had licensing for software. (So: not exactly a performa bundle.)
I'm sure there was either a performa variant or a 6200 variant for a little less -- possibly good if you were upgrading your own Mac and a 6200 fit the bill as a "letter writing and grolier's encyclopedia machine for the kids" when paired with, say, the old 13-inch color monitor from the IIci you would be shedding. Looking at MacWorlds/MacUsers from the era could be instructive on this, but I would bet that there was probably something around the $1,699 price point.
If you had a 475/605, you likely paid somewhere between $980 and $1,499 or so for it in 1993-1994. A 610 was $1449 in a pretty baseline config in 1993, so if a PPC upgrade card to get you to a 50-66MHz CPU was $500 you were saving a third of the cost of a new machine. On the other hand, depending on what you already had with, you weren't also getting the 15-inch multi-scan display, a modem or new printer, a new copy of ClarisWorks, the newest encyclopedia, and so on, so there's a possibility that people who really did want the performa bundle would do better waiting for that, specifically.
Plus, Internet connectivity even in 1995 basically consisted of dialing in, fetching the mail and the news out of a few AOL or eWorld channels you picked, then perusing it at your leisure offline. It wouldn't be until a few years later that this wasn't a viable Internet workflow, because really, this is what I did even on my iMac, in like 2002. I'd hop online, fetch my mail, and then hop offline and peruse it later when I had time. A lot of this is because at the time you didn't have more than a few megs of mail storage quota, so the possibility of your email inbox filling up was varyingly mildly to very real.
(As an aside: at around this time, maybe a year or two later in like 1996-1997, SyQuest had built a cheap version of one of its big cartridge storage systems for Windows PCs. It used the parallel port, so it was exceedingly slow, but it strikes me as the perfect place to do periodic backup and archiving of different datasets and it always seemed like a bummer to me that that particular system didn't come to Mac. Of course if you look up reviews and posts about it from the time, it was quite problematic, a lot more problematic than zip would be until a few years down the line when the zip click of death started happening.)