A word not previously mentioned is adverse. Although similar to averse, averse typically relates to a person whereas adverse relates to some thing.
Revising your sample sentence slightly:
X has an adverse effect on my decision to buy the product. I am averse to X and therefore may not buy the product.
Both sentences tell us the likelihood of purchasing the product is diminished. The first emphasizes the detrimental aspect of the product, the second emphasizes the buyer's perspective.
"Averse" describes a person's negative feeling or bias against something: Bob is averse to flying so he always travels by bus or train. Many people are averse to purchasing upgrades if there is no backwards compatibility.
"Adverse" describes a thing's negative attribute or contrary nature: For Bob and his co-workers, skydiving was an adverse team building exercise. Many people consider a lack of backwards compatibility to be an adverse selling point for tech gadgets.
There are also some words that may be better in certain situations, depending on the nature of "X". Here are a few more alternatives that I did not see in other answers and when they might best apply:
X discourages you from purchasing the product (where X might be a person, such as your spouse or a negative reviewer, or cheap materials or poor manufacturing).
X disincentivizes you from purchasing the product (where X might be something that reduces a benefit of purchase, like a new tariff disincentivizing purchase of an imported good or the expiration of a rebate disincentivizing purchase of an electric car; or X could be some undesirable aspect that isn't specifically product-related, such as knowing you are supporting EvilCorp may be a disincentive to purchasing their product).
X deterred you from purchasing the product (where X is a possible negative consequence, such as "a lack of job security deterred me from buying a new car" or "fear of arrest deterred me from buying the illegal substance."