I'll get to the point... It's not cheap! But, it's also much less expensive than it was even 6 months ago with Pepwave's release of the Max Transit Duo! Prior to that, dual modem cellular embedded routers were double or triple the price. That said, here's what the prices are today (2020-Jul-29):
 Ultimate Road Warrior Bundle with MobileMark Antenna (Our Kit): $1345  MMH Dual Carrier Unlimited Data: $189 (First Month) $250/mo thereafter  Pepwave AP One AC Mini (Interior WiFi Access Point): $149  XPOL High Gain LTE MIMO Antenna: $182  WeBoost 25′ Telescoping Mounting Pole: $130  NETGEAR 8-Port Gigabit Ethernet Unmanaged PoE Switch ~$80  APC 600VA UPS Battery Backup & Surge Protector~$65
Add in maybe $100 in miscellaneous costs like ethernet cabling, roof junction, etc... We're looking at around $2300 initial investment and $250/mo for data. That's a lot and we get that. But we, like many others on the road full time, use the internet for our livelihood. Considering we're talking about home-like internet strapped to a box that moves all over the country, that's not too bad!
Another consideration is, you don't need all of this stuff at once. We did, so we could test all of it. One could easily start out with just the main kit and data plans for around $1500, and add the rest on later, if ever.