Actually herby
Using your number of 1 crit every 30 saints- it would cost about 3k gems to get 10 crit saintings on a hero from saint 1 through half angel 5.

NOw the number of cards .....hmmm

well based on my own success i get to half angel 5 usually in 25 cards
so 750 cards based on having to do that 30 times basically.

Still thats a lot of cards - but say do that on a hero like valla or the prophet. thats 375k spirits or so. That would take about 7.5b credits on a tuesday which at the rate many of us are saving credits is about 4 months. But possible cut down to 3 months with using tickets from CWF and then add in getting teh right card on a spin or from broker you could cut another week off that.

SO this is a lot to do. Granted probably not something many of us veteran players would bother with doing. But lets say the next execdude comes along, starts on a new server, uses this strategy from day 1 and dumps enough money to get to VIP 7-9. 6 or 7 months into the game they could have a valla that is more powerful then any other hero out there, or a nekt that is practically unhittable. Once again not likely but possible.

SO maybe im over reacting a bit - but im sure i havent thought all the possibilities through myself.
Getting heores that the first 15 sainting are nothing but golds is not going to be that expensive. maybe 200 cards and 400-500 gems