Rim Bolts Question

[MapleLawn740]

Just brought a set of BBS rc 090 Style 5 - I never refinished rims before so I have a few questions
What type of bolts do I order not sure whats a good price also is should i powder coat or just paint the center mash ?

My budget for all 4 rims is around 400.

[MapleLawn740]

Refinishing rims -bolts are from fiftyfive52