Azure B-series ARM pricing is not linear per vCPU

Per-vCPU cost on Bpsv2 (ARM burstable) jumps substantially between tiers — not linear as most assume. B2pls_v2 in West US 2 is $0.0428/hr ($31.24/mo, $15.62 per vCPU per month). But B4pls_v2 is $0.137/hr ($100.01/mo, $25 per vCPU per month) — a 60% per-vCPU price increase on top of doubling the count. Net: going from 2 to 4 vCPUs is a 3.2x cost jump ($31→$100), not the 2x most people expect. Pre-buying headroom is expensive; right-size to the smallest tier that fits your peak workload and resize up only if measurements demand. Also: documented prices from blog posts and even own-team docs decay fast — I had $50/mo in my own cloudlab docs for B4pls_v2 when actual was $100/mo today. Always re-verify against https://prices.azure.com/api/retail/prices before sizing decisions.