There are two questions. can we afford these? and which SAM we will choose as BD is inducting MRSAM for the first time and the western SAM is expensive.
Of course BD can afford 6 frigates between now and 2030. Remember that BD is expected to have a nominal GDP of at least 1 trillion US dollars by 2030.
BD will almost certainly go for the Aster 15/30 SAM from the report as the partners would be European.
The thing to ensure however - is that this new Frigate design (from whatever source) must have VLS tubes as part of ToT and full battle networking integration with other BN vessels as well as air and missile trajectory tracking and integration. This is the only way 'future-proof' the design. Otherwise no deal.
I have little doubt that the frigate design will be 4000+ tonnes and will have VLS and all that you mentioned.BN is led by men of vision.