My partner is Jewish from the Boston area. We just bought a fixer upper house.
I would like to get her a mezuzah for our new place but there are so many to choose from.
Can you help?
A "mezuzah" as we use the term is made up of 2 items -- the parchment inside and the case which the rest of the world sees.
While we often spend time and money trying to get a nice case -- something pretty, and worthy of being shown off (or durable, depending on which door you are putting it on) the case is almost irrelevant. The essence is the parchment inside. Prices vary, often based on the size of the parchment and the skill of the scribe who hand-wrote it, but the content is always the same.
So if you are looking for a proper parchment, go to a Judaica store and look for one that will fit the case which you think is nice, but spend the money on a nicer parchment, not on a fancy holder.
You say your partner is from Boston. If you are buying in Boston or the environs, go to Harvard Street in Brookline, to a Judaica store there. If you are elsewhere which has a Jewish community, check out the stores, or take a look at online resources (though I am always skittish about buying a parchment which I haven't looked at first, myself).
Two additional thoughts in addition to rosends's answer
Many doors in the house need a mezuza (see here for details) - I realize it might sound a bit daunting if you are "just starting" but "no one should ignore the law" - the main door of the house should be the first one to start with
A second trusted online source is stam.net - both them and Hasofer (Danno's recommendation) are reliable sources - beware of prices that look too low - you do get what you pay for with mezuzot and there is much fraud (e.g., parchments invalid according to Jewish law) in the market, especially online