I've thought for a while that the other altar preps should give you your selected altar as a 4th altar, in order to compete.
Be mindful of how the Earthmother would interact with such a change. The biggest problem is that she's
way too easy to desecrate, and her prep penalty is non-existant if you don't worship her (or only worship her briefly before converting). This would essentially turn an Earthmother + burn cure prep into a super-powered version of the 25 piety prep the devs killed off for good reason.
1) 50 gold
If you're on a scenario that merits bringing your full force to bear, money is no object. If you're playing on other scenarios then this should be unnecessary, and playing the religious lottory with no church preps is more fun (IMO). While I can understand prepping JJ or Dracul for a "Ding Max" PQI or Taurog for a "Warmonger" PQI, for your average case scenario I see no reason to use church preps.
I will agree that the prep is pricey, but it's one of the more powerful preps so that's understandable.
Please keep in mind that these are the comments of a veteran. I realize a less experienced player who has to deal with the meta-game economy and struggles with lower-difficulty dungeons may have a different experience.
2) You might roll 4 poopy altars.
Your odds of that drop substantially if you're even moderately flexible.
Let's break it down:
* If there's one specific altar you absolutely must have, there's a 44% chance you will get it.
* If there are only two altars you'd be happy with, there's a 72% chance you will find at least one of them.
* If there are three altars you would be happy with, there is an 88% chance you will find at least one of them.
* If there are four altars you would be happy with, there is a 95% chance you will find at least one of them.
The only time this gets really scummy is if there is
one god that you absolutely must have no matter what. If you have two gods, it's moderately scummy. Once we move to "any of these three would be great" we're outside of scum territory; a 12% chance of being screwed over is much lower than a horrific glyph or shop pool.
I find by this point that pretty much every class I play has a variety of altars that can work, especially with the broader conversion and desecration options opened up by having four altars.