I think as well as buying mob Spawners at spawn you should be able to mine them with a silk touch pickaxe I've tested it before and it did not work. Could you please add this I'm sure a lot of people would like it.
This has advantages and disadvantages, Advantage: You'll be rich if you ever find them. Their all over the place if you have a hacked client, if you press (key y) you will be able to see chest anywhere in your radius. Sometimes, you will find mini dungeons that contain a spawner. Disadvantage: It could become to over powerful. You could betray a faction and mine all of the spawners. In the server that use spawners, Money is valuable, Use it wisely. You shouldn't have a second chance at it. Use your placement carefully. Hope this helped
Betraying your faction would make you rich and sometimes betraying is the fun in prison and factions.
Isn't this the whole point of factions? To raid, betray and inside? Also, I don't think that is a disadvantage. Raiding a base and getting rich is really quite good.