in my experience (Eu, datacenter/ISP space) connectivity is either sold based on 99percentile commitments (aka, you pay for sending us this amount of traffic, anything over this gets you billed extra) or based on a minimum commitment for the traffic you send. (atleast X amount of bandwith) or it is based on a flat free principle where you pay an upfront cost for the setup and the rest is a base price for X amount of bits per seconds.
It depends a lot on what kind of connection you require, and things like oversubscription and congestion control also come into play.
Peering ports with IXP's are usually flat rate, while ports in datacenters to end customers usually have more complex constructs.
Hyperscaler bandwith is notoriously expensive.
for instance, a 100Gbps port on the AMS-IX is 2500$[1].
Now, you need to account for extra costs to actually use this port (some IP space, ASN number etc) but even with all that added up i think you will not get much more expensive then 400$ per month averaged in total over a year.
Now what makes comparing difficult is that hyperscalers are not transparant when it comes to connectivity costs. Looking at egress fees for example:
AWS seems to charge 1 cent per Gigabyte transferred for egress fees.
If we send data at line rate across our 100Gbps for an entire month we get the following:
100gbps = 12.5Gigabytes per second.
12.5 * 2 629 743 83 (number of seconds in a month) = 32871797875 Gigabytes
32871797875 / 0,001$ = 3.287.179,7875
thats 3,2 million dollars... compared to roughly 4000!
AWS also seems to offer "dedicated connections". at roughly 22 dollars per hour [3] (no clue if this is even comparble to an IXP port, but the comparison would still be fun to make).
22$ x 720 (hours per month = 15.840$, or roughly 3times the IXP port price.
In both cases, you are getting absolutely shafted by egress prices at cloud providers compared to doing it yourself.
[1] https://www.ams-ix.net/ams/pricing-us
[2] https://aws.amazon.com/ec2/pricing/on-demand/
[3] https://aws.amazon.com/directconnect/pricing/