Can anyone recommend a good firewall/router that can load balance multiple wan connections. I would like to make use a second mobile broadband connection. I don't have to have a device that supports mobile broadband because I already have a router that I can insert the sim into and then run Ethernet to a load balanced router. If anyone could recommend a device that accepts a sim or USB modem all the better but it would need to also support European LTE networks. Another feature that would be important to me would be a data monitor/ data cap feature that I can use to track or cut off one of the WAN connections if it goes over a certain usage each month.
Currently the only devices I have come across that can do this are the Peplink balance routers which are quite expensive. I have the hardware to and I have used pfsense to load balance previously and it worked well however it does not seem to have a good accurate way to cut off a connection after a certain amount of data (at least I didn't see a way) and I also found the data usage monitor/graphs to be a bit flakey. Perhaps there is an alternative open source firewall software that would work better for me or perhaps someone knows an addon for pfsense that might do what I am looking for?
EDIT: If I have the purchase hardware I am willing to spend about $500 if I need to but ideally would like to spend under 200 or use software like pfsense.