It's heavily dependent on league rules. Major factors are:
1. Number of teams, and also roster/starting spots.
2. Cap amount.
3. Dynasty or keeper - I'm sure there are single year cap leagues, but it's not something I'd think is common.
4. League scoring.
5. Other rules that are relevant, such as moving players up & down to a minors/farm roster, or cutting unwanted contracts.
Ideally you want a guy that performs well with a cheap cap hit, but for goalies, those are usually guys who take over jobs while still under contract, and once they get established, they get paid. Another option is to not necessarily look at a tandem from 2 different teams, but say, the tandem from a good team, so you avoid having 2 guys who both are the 1B. You can only keep 1 golaie, so the idea should be to get either a starter who isn't super expensive, or a cheap guy who can grow into starting.
The only cap league that I'm in, I would LOVE to have Vasilevkiy. Our cap limit is large, over 100M, plus he's the best goalie in fantasy right now. He & Hellebuyck are the 2 big money guys I'd take easily. Unlike skaters, who can underperform, goalies can actively hurt you. However, we also have a 12 team league with 75 player rosters (50+ players in the minors system) and waivers where guys who make too much have to clear to go down to the minors.