These are roughly the costs that one immigrant would be spending in 5/6 years of their immigration journey. Take note, it will increase every year.
Fiance(e) and Spouse Visa £956 FLR(M) or extension (x2 for the ones who arrived as fiancees) £649 ILR £1,500
Naturalisation £1,005
Extras:
BRP (post office cost) £19.20 PEO application £400
On top of that, the sponsor must be earning £18,600.