Elizabeth gave you a great answer. In your shoes, I would take a little time (assuming your rental agreement is not up on December 31st) and do some information gathering.
The first place I suggest you start would be to get a very clear understanding of your personal financial situation. Lending has changed a lot in the last year, and many loan programs that were available even a few months ago (or heck - last week even) are no longer available. If you need 100% financing, have a credit score under 700, or have income that is not easily documented, do not waste time talking to a loan officer - programs to accommodate these circumstances are becoming difficult to afford/obtain. I would start by talking to a reputable, local loan officer. Get a referral from a friend, family member, colleague, etc. to a loan officer they trust and have successfully completed a loan transaction with. If you do not have any luck getting a referral, I suggest calling Marlena Olson with the Vitek Mortgage Group at 916-486-6900. Whichever loan officer you select, he/she will run your credit, and analyze this along with your income, savings, assets, etc. Determine your budget, and find out what programs are available to you and what your monthly payment will be. Make sure the monthly payment amount includes your principle, interest, property taxes, and insurance.
While you are figuring out your financial standing and purchasing power, if you are looking to live in 95818 (Land Park / Curtis Park), as Elizabeth suggested - take a Sunday and visit local open houses...there should be no shortage of them in those neighborhoods. Educate yourself with regard to architectural style, property conditions, location within those neighborhoods, etc. Prices will vary in those neighborhoods based on all of those factors and more. While you are at the open houses, talk to the agents who are hosting them. Ask lots of questions. If you are unable to go to weekend open houses, get in your car and drive different streets there. Get a feel for the area.
I may regret saying this, but if you do not want to contact a local title company to pull up recent comparable sales - you could try Zillow.com. While most "Zestimates" (what Zillow refers to as its "estimate of value") are grossly inaccurate in 95818, you will be able to look at recent sales data in those areas. You will have to educate yourself to determine which recent sales are actually comparable to the house you rent. Again - go to open houses, drive different streets, talk to agents, etc.
Once you have all of your arrows in your quiver, if you have decided that you want to attempt to purchase your landlord's house - my suggestion would be to call and ask if he/she is interested in selling. Meet him/her at the house and be prepared to back up whatever you have decided with facts. If you are not used to negotiation, you might consider purchasing a book on the subject. You do not need a Realtor to facilitate a purchase transaction. There are, however, many nuances to the purchase of property, and if you do not use a Realtor, definitely consult with an attorney, inspectors, appraisers, etc. If you do decide to use the services of Realtor (on this property or any other) - please pick one who specializes in Land Park / Curtis Park. Elizabeth Weintraub and I both work in these areas quite a bit. We are both top producers, and Elizabeth is a kick.
Best of luck to you!...and happy new year!