I see the same problem, mainly for new players (well with my 4 weeks I'm still new as well), but I will write a how-to post on rentals after the season is over.
I think I will be downgraded to Bronze league as well, so I will try to update also ranked game win rewards, so it will be possible to calculate how feasible the strategy is. I'm currently in Silver 2, I don't believe I will get higher with the current rental prices...
But in general I hope that the prices will normalize a bit, so that owning will be an option again! Good luck with the packs!