Tier 2 requires 200Cr and there is a listing fee for every item you put on the AH. Everyone has some bad materials no one is going to buy but the vendor(@Scrap Metal). Sometimes I am tight on money and would like to go instance or AH some stuff i have and I dont have the 200 CR or enough for the listing fee. I do not enjoy going to the bazaar just to sell some items so i can go back to town square or the arcade and continue w/ spiral knights. My solution is to just to put 1 vendor in town square and another in the arcade, I could care less what they sell...
supreh, Tier 2 only costs crowns to access if you have not completed a full Tier 1 run on that gate first. (This status is per-gate, and resets when the gate goes off the board).
So if you know you're going to do a ton of Tier 2 runs, such as JK runs, it would behoove you to complete a T1 run first, because let's say you do 20 T2 runs on that gate, that's 4,000 crowns right there you could've saved by doing one T1 run. It has to be a full run, so make sure you start your own T1 party and wait for others to join in the start lobby.
Same principle applies to paying for T3 runs, I forget the crown cost but the idea is the same.