I'd go with Cisco's of some kind myself, as said catalyst express units can be had for <£800 quite easily. That's less than £35 a port which is pretty good and I suspect a fairly small cost compared to the cameras themselves.
I'd also say that generally when you're budgeting the solution you incorporate the cost of the switchport into the unit cost surely? Everywhere I've worked that's been done for everything from servers to desktops and ip phones, eliminates nasty surprises and trying to find network capacity on the cheap...