Quick copy-paste, but helpful. Items stay in the bank, so you have to return there to get them.
Character Bank
Level------Level---Slots----Cost------------Details
1---------0-------12-------$0--------------Initial starting bank
3---------1-------15-------$12,565---------Purchasable upgrade
8---------2-------18-------$26,397---------Purchasable upgrade
13--------3-------21-------$55,454---------Purchasable upgrade
18--------4-------24-------$116,466--------Purchasable upgrade
23--------5-------27-------$244,629--------Purchasable upgrade
28--------6-------30-------$513,807--------Purchasable upgrade
33--------7-------33-------$1,079,176------Purchasable upgrade
____________Must be on Play-through #2_________________
38--------8-------36-------$2,266,642------Purchasable upgrade
43--------9-------39-------$4,760,721------Purchasable upgrade
____________Must be on Play-through #2.5_______
48--------10------42-------$9,999,143------Purchasable upgrade