Can I get even lower prices with budget airlines using a VPN?

Yes, you can get lower prices for flights using a VPN. For some reason (most likely due to the difference in supply and demand), airlines charge different prices for passengers from different countries - even if it's the same flight. So I'd highly recommend getting a VPN that has a variety of countries to choose from (like Nordlayer or IP Vanish), changing your location with it, and finding the best price for your flight.