True, DEC Tokens will really play a huge role in the guilds system. You're right every member needs to contribute 90K DECs to get the 2.71 Million DECs necessary to get a guild to the max level at Level 10. And with DECs going up in prices recently, that just got more expensive over the last week.
Thankfully, there are some guilds where membership dues are sponsored for you. @peakmonsters, for example, has a "Premiere Guild" where they pay for all the DEC needed for upgrades. The guild is at Level 8 now, all paid for by peakmonsters. The catch is that you have to be a user of the peakmonsters.com marketplace and you need to be a Champions League player. You can also be demoted to their lower, non-sponsored guild if another player beats you in the rankings.
It's all good, though because they're building their lower-ranked, non-sponsored league to be a pretty nice place, too. It's also their way of encouraging active players and eliminating "drama" within the league.
I'm a Senior Member of the @contestkings guild. You just pay 10 installments of 10K DEC and you are in. We have 6 positions available so far. You need to pay the first 10K DEC in the first 24 hours Read more about it:
https://steemit.com/guild/@contestkings/6-positions-available-in-the-contest-kings-splinterlands-guild
https://steemit.com/contestkings/@contestkings/contest-kings-splinterlands-guild-structure-summary