Azure VPN is charged on two factors:
- Number of connections or tunnels
- Amount of data sent over VPN
There are multiple tiers available, if you had gone with the basic tier this would cost about $30 a month for the base fee, which include 10 S2S tunnels and 128 P2S tunnels, with bandwidth up to 100Mbs. So if you saw bills of $200 a month you are either using a higher tier, or send more data. Can you check the tier you used and see if you can reduce it?