It's hard to say. Any of the big places are going to be an 'email us for a quote' pricing model.

https://ussignal.com/uploads/general/Grand-Rapids-East-Data-...

I haven't rented any space in a while but I'm going to assume $400/month is about the cheapest that you would be able to get a half a cabinet.

And of course, that depends on how much bandwidth you need, how much power you need, are you running top-tier connectivity or something like Cogent/he.net...