> Colos frequently forbid the use of small UPS's for a variety of
> reasons.In my experience they always need to be connected to the EPO switch,
which poses it's own risks. Plus try to find a UPS with that feature
for reasonable prices.
APC says it's available on the SUA2200RM2U and SUA3000RM2U, and lists
it as optional for the APC SUA1500RM2U.
I would consider all of these to be reasonably priced.
Which leads me to this question: What questions do you ask any
potential colocation provider to determine if they are built out to
your needs?
See if they'll guarantee diverse power as part of the contract. 
It's disappointing to find a colo that feeds you your primary and
redundant power off the same UPS.
... JG