Well you could still go the route of 5 to 3.3V PSU set up, use same 5V source to directly power USB cam via its USB power pins, do some soldering etc.
But overall the $5 Omega2 figure is as much hype as for the RPi0 which is still not generally available ! 5V tolerance ( as for ESP) or 5V external ( with onboard 3.3V conversion) OTG USB receptacle would really have helped, but ... both RPi and Omega2 want to sell expensive accessories.
The other interesting board I looked at was OrangePi Zero, plus other OPis. But the WiFi driver on OPi0 isn't available owing to the obscure XR819 wifi chip instead of the standard Realtek ones. The BoM comes to $20 if you include memory, casing, PSU and misc.
Meanwhile Android Boxes fully loaded, very hackable, are down to $24-25 already ! Unless you really want single purpose boards like for $5 Sonoff WiFi controllers featuring ESP8266 or USB cam WiFi webstreaming only.