We currently operate three clusters of collocated machines in different data centers.
Recently, I became aware that our newest data center will offer to cross connect us to a bandwidth provider free of charge.
In the past, I never really investigated a cross connect for bandwidth because I figured that the rates would be similar to what we are paying the colo now and that it would reduce our resiliency (because we would only be using one or two carriers for IP, where as the colo uses, say 8 different providers).
Then I saw an ad for hurricane electric internet services (http://he.net/cgi-bin/ip_transit_quote) that gave a price for IP transit at $1/Mbs, which is much better than the $30/Mb we pay for the blended bandwidth.
What are people out there typically paying for bandwith via cross connect and how hard is to setup? Is my understanding that what you do is open agreemetns with two or three ISPs, cross connect to them and then configure your top of rack router on their network. Can you really get IP transit down to a couple of dollars per megabit per month just by doing the routing yourself?
Or, is my understanding of cross connection fundamentally wrong?
A cross connect is typically a cable from A to B in a data centre. As Andrew H says, often comes with a setup fee and possibly a monthly recurring.
If you're not running BGP with your own autonomous system (and IP range) and you connect to a new bandwidth provider they will assign you a new IP range. You will probably have to renumber your machines.
If you're not going to be multihomed (with BGP/AS number/own IP range) it would be better if you kept with a tier 2 ISP (ie. one that has many uplinks). I think HE are a bigger tier 2 ISP with a very good reputation, so, that probably won't be a problem.
If you look at other providers (perhaps Cogent/Level3) who are Tier 1, beware if you're singled homed. Tier 1 providers some times have peering disputes and those who are single homed to them can get bitten in the arse.
As far as I know, "cross-connects to a bandwidth provider" literally means they will put a cable down from your rack to that provider's switch in a carrier room or cage. This might cost a few hundred dollars and then perhaps $40 a month in maintenance costs, so it doesn't seem to me that it's worth a whole lot, because it doesn't sound to me like they are offering any actual IP transit for free. I recommend you get them to clarify the exact nature of the offer. Terminology in this area can vary from person to person.
Regarding your specific questions:
"What are people out there typically paying for bandwidth via cross connect and how hard is to setup?"
I can't say what we pay but if you have a spare port on your router, you would establish a route to the new ISP's upstream router and perhaps advertise your subnet via BGP. Do you do this to advertise routes to your three clusters at the moment, or do you use DNS to get traffic to each?
"Can you really get IP transit down to a couple of dollars per megabit per month just by doing the routing yourself?"
Not sure about the price, however in my experience if you can get $1 per mb then you should rebadge it and sell it - some ISPs might bite your hand off! But I guess the US market is very different to the UK.
"Or, is my understanding of cross connection fundamentally wrong?"
I'd wager that the cross-connects offer is simply to run a cable for free and charge no maintenance on it, but I could be mistaken.