If I were to only purchase the Graviturgy wizard from explorers guide to wild mount, would I get the dunamancy spells associated with it? I would assume so but they are listed separately and for equal prices so I'm concerned that I might not get them. Is this the case?

No you would need to get the spells as well either by buying them or the whole book.

Ok thank you! But would I still be able to use them as part of the graviturgist class? As in would they be available just for the graviturgist class but I'd be unable to give them to any other class. If not that seems like a glaring design flaw given dunamancy spells are one of the major benifits of choosing a dunamancy subclass.

The spells will be usable for the relevant dunamancy subclass. Some are available for both Gravity and Chrono subclasses, some are specific to one or the other. See the list below and note the asterisks (*). 

However, if you own the spells and your DM permits you to use other wizard subclasses with these spells then you can create homebrew copies and in the "available for" section remove the gravity and chono subclasses and just add in wizard - the spell would then be available for all wizards. 

Buying the subclass, even the dunamancy ones, will not unlock the spells. The spells must be purchased separately.