I’ll preface this by saying that your landlord is nickel and diming you and that really sucks, but is common. The short answer to “can they charge us this?” is “yes.”

Raising the rent by $100 isn’t out of step with what’s common and is allowed by law, and I honestly don’t think your rent seems that high these days, especially for a house in Lakeside.

You’ll also never be able to prove what fair market value of the house is; landlords can basically charge whatever someone will rent it for. Any landlord will just decline to renew your lease if you try because there are next to no tenant protections in Virginia. Technically that could be considered retaliation for asserting your rights under the landlord tenant act, but good luck proving it.

All of this is to say that you may pay less with another landlord, but with the vacancy rate what it is, especially in your area, you should probably stay put unless you have other issues with them.

ETA certainly look around, but I don’t think you’ll do that much better.