I am in a bit of a dilemna here, long story short we decided to rent a room to my DW's aunt - we have way more house than we need and it seemed like a good idea to make use of the space as well as do somewhat of a good deed. The aunt is a pleasant person and will not be any bother as far as noise, cleanliness etc. She will help cook and clean as a member of the household as far as I can tell. I initially thought it was supposed to be for a few months, so did not really care to negotiate or ask for much (was just going to accept whatever was offered without any concerns), unfortunately the details have changed and it has shifted to a long term situation and I need an unbiased opinion to help me determine a fair $dollar amount.
I am going to spare the details and drama of what happened, miscommunication by DW etc and get to the point, she is now looking to stay for up to 2 years.
Because of the initial details we basically just said to give us whatever you feel is fair (The rate that was offered is essentially to take the bachelor apartment rate in your city and divide it by 3.5-4.5, I would call it more of a courtesy gift than a rent at this point.)
From their perspective the layout is not at all designed for a tenant. There is no separate entrance, kitchen, they do not have a washroom on their floor and the bedroom is right off of our basement living room (which means in my mind I will be surrendering my main living room most nights). They are also only going to be staying 4 nights a week and commuting back and forth to their family Friday - Sunday as they will not all be moving here for the 2 years for personal reasons. Since we are getting into the $ and cents from a rent perspective obviously utilities, WIFI and premium cable are provided.
I am not looking to make market rent off of this, as this was supposed to just be a bit of a favour, however I just bought this place and I will be damned if I will lose enjoyment of my property for 2 years (see above re: bad layout) to subsidize someone else's bank account. Also keep in mind there is no component of financial need on any side of this negotiation, although us being 27 and her being a late 40s professional who just took a big full-time promotion (reason for coming in first place) I would not be surprised if her income is nearing both of ours combined.
I gave some extra details but I don't really need anyone to comment on who is right or who is wrong just on how you would decide a fair amount taking all the factors into consideration including that it is family. Assume that a bad bachelor apartment goes for $700/month and a mediocre 1 bedroom for $850 in the local area with no utilities included.